I've gone where you're headed.
My husband purchased a new smaller and more portable laptop for himself so I got handed down his old Toshiba tectra. My main computer for the last 3 years had been an iMac which I ended up selling.
I figured this was a good time to sell the iMac because the 3yr applecare (which I never even had to use) was about to expire, and also as there is a rumor that Apple is bringing new ones out. So I thought it was a case of sell now to recoup the most $$ I could expect to.
Anyway, yeah within the first week of the Mac having been sold I found a trojan on the laptop! Ha. But a change in the antivirus that was being used took care of that (I'm onto Avira as AVG free is apparently useless these days).
And Mac might not get viruses but unless you have some sort of virus software on it how would you even know? Same goes for windows, I wouldn't have know about the trojan if I hadn't installed bit defender on my firefox browser and scanned the computer.
I had no apprehension about switching back, after 3yrs of solely using the Mac I felt very out of touch with windows, and from what I've seen windows has been doing mostly good things. Namely windows 7, which I look forward to using in the future and was one good reason to go back to it (somewhat Mac like) even though I am using XP at the moment. I also thought about the fact that the kids will be using windows at school, and I wasn't willing to dish out the money for a full version of windows just to run on the Mac when for just a bit more you could probably buy a whole new windows based laptop! And the last factor is that my Husband isn't really a fan of the Mac. Well ok I was a little apprehensive of having to deal with viruses and my kids potentially using the internet and picking them up (not so much a worry with the Mac).
But I tell you what, the fonts and display quality on this laptop compared to my iMac took a bit of getting used to, it just left me feeling like I was going back to some sort of crappy old technology (in regards to how nice the fonts, colours etc look and the colour schemes of xp compared to getting used to a Mac with the nice 20" screen). Mind you Vista and Win 7 have a bit more "eye candy" so it's a negligent issue and I'm already used to it now.
Anyway as for laptops when I eventually hand this one on to the kids I'll be looking at Toshiba or Asus and maybe even Dell, they're meant to be three of the better brands. We've had a few toshibas, the first one had overheating problems due to constantly sucking up dust (intake fans were just in the wrong spot I think it was a real problem), luckily that one was a rental so was sent in for a new fan etc probably every 3 months or so (no matter how hard we tried to keep the environment dust free), no such trouble with the current one though (3 yrs old like the Mac). My Husband didn't do that much research into his new purchase but ended up with another Toshiba, L640 somethign from Dick Smiths, pretty much had the best spec considering it was a 14" screen, well except the one he got doesn't have dedicated graphics which my non gamer husband doesn't pay any attention to, much to my displeasure.
Only thing I'm hearing is some sort of issues to do with the new sandy bridge processors, so I'd consider snapping up a bargain of the current models when they're being cleared out or holding off until some bugs are ironed out with the new ones that are out or are coming out first.