CYBORG9  First, pay $70 for Virusbarrier, then after using it for a year pay $30 per year for virus definition updates? No way in hell will I do that regardless of how good it may be.

Make it a lot more reasonably priced and we'll talk, but not before then.

And there's no real Mac virus threat out there currently.  
(Version 10.5.8)

ROBOTANK  Would I pay $70 for this? Probably not, but that's not a reflection of its quality, only the necessity (or lack thereof) of Macintosh AV software in general. Since getting this app with the latest MacUpdate bundle I've been very impressed with it. The realtime scanner is completely unobtrusive: it uses no noticeable amount of CPU or RAM and doesn't slow down operation. I haven't picked up any viruses for it to detect, but the professional reviews all agree that its detection rules are thorough and up to date. As always in this tired debate, the question comes down to whether or not you need _any_ AV software on your Mac. You probably don't, but if you think you do, VB X5 is certainly worth a look.  
(Version 10.5.5)

TOM46  This thing is a god-awful memory hog. Thank goodness it comes with an uninstaller!  
(Version 10.5.6)

TOMEM  I take it back. There is an uninstaller integral with the installer. And VirusBarrier plays MUCH better with other processes than MacAfee VirusScanner, BY FAR! And it gives much better feedback on the process of scanning.   
(Version 10.5.5)

PLUT0  Maybe there are few virus threats to the Mac right now but the thing that the community needs to realize is that they will come. When that time arrives, we need to have developers who are responsive to the community and have grown along with OS 10. I probably will not use the current Virus Barrier that I have bought in the MacUpdate package, but I do believe that I should be helping to support efforts like this for the future. I think all of us really need to look at the applications that we use and give some longer-term direction to the developers as to what works and what doesn't.

Personally, for a virus detector, I would like to see a fast, small-footprint bloodhound that receives network updates whenever there is spare bandwidth and digs around in my files looking for decay and danger. Perhaps it could also be indexing stuff, to be handed off to the operating system.   
(Version 10.5.5)

PETER_EARTHMAN  I am working with OS X for about 6 years now. Never got one problem with virus/trojans.

Is it necessary to use a virus killer? As of yet I do think not.

But when OS X is gaining popularity it maybe possible we are going to see a grow in trojans.

For now I do not need/want to use a virus killer like this.  
(Version 10.5.9)

REDANZL  I acquired Virus Barrier as part of one of the MacUpdate bundles, and I've had problems with the real-time scanner, where occasionally, the virusbarriers start hogging the CPU to the extent that my Powerbook G4 was almost unusable. I've disabled real-time scanning, and let it run scheduled scans instead (it's never found a virus so far, which doesn't surprise me).

But I must say that NetUpdate is truly an annoying application. It must have been written by a Windows programmer, because instead of bouncing an icon on the dock when it opens like all well-behaved Mac apps do, it barges to the foreground to announce that updates are available. I click the OK button, click the Update button (why not make Update an option of the announcement screen?), enter my login password at the prompt, and it starts updating. I resume whatever I was doing (such as web surfing), and when the update is complete, NetUpdate bulls it's way to the foreground again to let me know that it's finished. I click OK to acknowledge that it's done, and it checks for updates again. On the occasions that it finds another update, I have to go through the entire process again, including entering my password, cursing it as it interrupts whatever I was doing. Surely this intrusive, cumbersome process could be streamlined.  
(Version 10.5.8)

HELIOS9  Be aware that after using Virusbarrier for the first year, it you want to continue getting new-virus updates after that you'll have to shell out about $30 yearly for them. Is Virusbarrier really worth the price?  
(Version 10.5.5)

SYZZYGY  Since Virusbarrier apparently causes all manner of grief to Mac Users who install and use it, and since there are no active Mac Viruses out there and since it's overpriced at $70 plus $20 or $30 each year for virus definition updates, I'll jiust pass on this anti virus software and instead use the highly acclaimed and free ClamX to check for virii when I feel the need to do so.  
(Version 10.5.5)

JAMESKITTY  $70 seems like a lot to just clean out some bad macros from office documents... Maybe if there were actual Mac viruses out there, it wouldn't sound so extreme.  
(Version 10.5.4)