MISHA  MacTech has just published their comprehensive head-to-head comparison between Fusion 3 and Parallels 5 (3,500 benchmarks performed).

"In the majority of overall averages of our tests, Parallels Desktop 5 is the clear winner running 30% faster than VMware Fusion 3.0.1 with Windows XP, and 43% faster with Windows 7."

More: http://www.mactech.com/articles/special/1002-VirtualizationHeadToHead  
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HEADCRASH  I highly recommend that you steer yourself towards the far superior product: VMWare's Fusion.

Parallels started out at as a great application, but as features were added and system software changed, Parallels quickly fell behind. As of the last few versions, Parallels became unusable because of a confounding "Failed to allocate specified amount of memory" bug. (See some of their forum postings).

The coffin in the nail was the *terrible* customer support that they "provided." For a fee. That you had to wait on hold for an answer to. That didn't help. At all.

The hard-drive conversion utility made the switch a no-pain, no-brainer.

VMWare's Fusion is solid .. have had very few problems with it, it's been speedy, and they've got superior customer support.

Make the switch, you won't look back.  
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PETER CROSBY  When my work kindly purchased a copy of Windows 7 Ultimate for my home PC I kindly accepted. So I tried VM Fusion and Parallels and I have to say that Parallels is well worth the money.

I had been using version 4 which had no support for Windows 7. I stumped up the cash for the upgrade and never looked back.

A good honest VM program that will integrate well into your setup.

I would highly recommend paying for this application.  
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PCHARLES67  While I agree that Parallels is a bit more expensive to upgrade than VMWare Fusion, I have found it to be the superior product at this point and worthy of the upgrade price. I started off with an early version of Parallel when I bought the first Intel iMac (white 17inch). When I bought my first Intel Macbook (Black 2.4GHz) I decided to go with Fusion 2 because it seemed to work for my needs and I liked the educational pricing. I tried demos of Parallels 3, and found them extremely clunky. However, as part of a MacUpdate package I got Parallels 4 and decided to give it a try. I was pleasantly surprised how fast and functional it was and I am even more impressed with Parallels 5.

The biggest thing is how Parallels and Fusion handle Bootcamp partitions. Everytime I started a bootcamp partition inside Fusion it would ask for an administrators password, which as a royal pain when trying to run using non-administrator accounts. I am not sure if it is a quirk of my systems, but I could never figure out how to bypass this. Parallels does not ask for an administrator password to load a bootcamp partition and I can tell you that sold me on Parallels there and then.

A couple of other things:

1. I tried a boot test with a file created on the virtual machine. What I did was create a word document in Bootcamp and then use it to boot the virtual machine. In every case Parallels was able to boot, load Word, and load the file quickly and without fuss. Never was I able to get fusion to do the same. For one it would stop and ask for a password, and then it would fail to open word.

2. Boot speeds are pretty similar, but I recon parallels is a touch faster at loading.

3. Crystal is really cool, but I like the fusion menu bar icons and the way it handles the start menu better than I like Parallels version.

4. I seem to have less problems with USB items using Parallels than I did with Fusion, but that could just be a function of the newer software.

5. I wish there was an easier way to shut down the virtual machine without going to the start menu. When you quite Parallels it asks if you want to suspend or stop, but does not offer shutdown. Since I am running from a bootcamp partition, I cannot suspend. As a result, If I press my powerbutton to run a shutdown I get stuck because Parallels cannot initiate a shutdown. Not sure if the newer fusion can.

Overall, I think Parallels has a winner with this product. It is far superior to its previous products and while the upgrade is a bit more expensive than Fusion, I feel it is worth the extra money not to need the password on boot. When you consider how much extra some other companies charge (Microsoft, Adobe, and so on) it is not that bad.  
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ERIC DURBROW  I also want to want potential buyers about Parallels upgrade. Not only is it overpriced compared to Fusion and free alternatives but it is also not reliable. As a Parallels 4.0 user one cannot upgrade to the latest 4.0.3848 version using a netgear router. And three emails to tech support (2 different addresses) have not been answered. Please avoid this. It may work but Fusion is cheaper and you are less likely to have upgrade hassles.   
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TRASHIE  Okay firstly this application is very good v5 is very fast. No complaints on the software in general. If you want to pay for this it does a nice job. So does it's competition.

I have given up on VM's just now as I find OSX is fully capable of surviving on it's own for ME! If you need win/linux that badly then buy a cheap PC (and oh you can find deals on PC's for next to nothing to run a basic win install). Why?

The cost of these upgrades is getting out of control for someone who is not a windows user. I have spent more on Parallels than I have with MS since I started to use their VM for XP. It is to the point if you work this out long term (if your a tinker user like me) your as cheap with one of these mini PC's or cheap notebooks. Then you get full native support. With networking and remote desktop applications your in business. Your OSX is then not having to do as much work so works nicely.

If your a mobile user of win and osx maybe this is worth it...most use Linux on servers (not desktops) so I am not sure it is a big deal Linux being in a VM (except for academic uses). Linux on desktops is not for most of us.

Don't miss read these apps are getting very good and DO have a place but if your like me...have a think...it may be cheaper and better to make use of more of the growing OSX support and use of cheaper native PC if win is not mission critical for you.

Anyway hope that makes some kind of sense....  
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ROBERTCOOGAN2  Overall, a very solid upgrade. But pricey! I paid 50 dollars for the upgrade and think that it is too much for what amounts to mostly bug fixes and speed improvements. But overall, it is very apparent that speed has improved. Transition from/to coherence mode is seamless now, before there was a very noticeable lag. Much easier to use this time around, much more user friendly. But Parallels needs to offer a better (cheaper) deal for the upgrade. I purchased 4.X two months ago and feel a little ripped off.  
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EANKOBERT1  Parallels is NOT WORTH IT

50 dollar upgrade or 80 to buy.

Fusion is 32... No Brainer...

Furthermore, parallels does not have old version on their website for you to download, if you buy online you are screwed when they come out with an update...

Runs well, but the support is awful unless you want to pay extra. Average 30 minute wait time on the phone....

Definitely find a different solution unless you are made of money and feeling charitable towards this business.  
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JEREMYAN  Outrageous upgrade pricing.

Unacceptable.  
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KENTR  Parallels is consistently updated and supported. Thanks!  
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