There is only ONE real issue with computers and software: THE USER.
I have a Dell laptop, and have had Dell laptops for almost 11 years now (I am on my 7th ... 6 were provided by work, I bought 1) and have NEVER had a problem. I seriously doubt I would have a problem with a HP or Mac either.
Most A/V proggies work just fine if you keep them updated and you pay attention to what you are downloading and what websites you go to. DILIGENCE is the best anti-virus.
The BEST advice is to actually learn about your PC and software to effectively use both with minimal hassle.
Well Dell laptops are very good providing you stay away from the low-end models and all the retail units.
As far as A/V software, I personally use AVG (was the only one that had 64-bit support when I first built my rig) but when my subscription runs out i'm going to install VIPRE.
To be truthful, a good A/V is only have the story for a clean machine. As long as you use a good browser (read: NOT internet explorer) with the right add-ons you'll be fine.
I personally use Firefox with Adblock Plus and Noscript and have not had to run a single virus scan with my A/V software yet.