I am only going to comment on Intego Virus Barrier 5, not just Virus barrier but the whole suite. Unless you have a huge hard drive on your laptop forget it. It's bloatware. Mind you this is not the free version I am rating, It scans all email, rejects mail that is spam. Users add names to this list when they receive spam, through daily updates you stay up-to-date. You can really customize your firewall and you can get rid of little snitch. It also lets you know when a document or app tries to phone home..
Did I say bloat? Now here is where the party ended. When your subscription is up and you have not purchased the next version of Intego suite, what do you do. There is no uninstaller. Apps like CleanApp and App Delete can't get it. there it is, always staring you in the face. You will find new remnants everyday. The solution is a complete erase and install of Snow Leopard and all other apps you own. There I said it.
Since there are known Trojans but no real viruses loose, it's not something you need. Weather you use mobileme or gmail, they all have pretty good spam filters.
If you want a little reassurance, I installed Sophos. It uses nearly no memory. Takes up little HD space. And it's free version is not slimmed down. It's the same software they sell to large corporations, it's free.
I hope I save someone the trouble of reinstalling everything. The software it's self is impressive. Does it work? I don't know, it never found a virus in the 2 years I used it. You decide if it's right for you.