I'm another one who came to console games through Sony's GT series. Started with GT2 (which someone actually gave me for free, along with the PS1!!), and was surprised that the thing actually modeled oversteer & understeer. Skipped GT3, but went through GT4 like a hurricane. Even bought the Logitech wheel for the thing.
I did PC games years ago with Sierra's "Indycar Racing 2", and tried it again when SHMBO bought me a combo pack of SimBin's "GTR 2" and "Race 07", but my PC is so burdened with other stuff right now that I can't get it to work very well.
I'm also a "recreational" guy when it comes to racing games. I'm an ex-SCCA club racer, and don't want to spend the time & cash on "virtual" racing that I spent on doing it for real. At the moment, I'm running Forza Motorsport 3" (and I'm an original member of the Triple Awsome League, AFAICT), and having great fun.
I guess "the answer" depends on what you're looking for. If you want the best virtual simulation of our sport (and would rather burn money on computers and plasma screens), I'd seriously recommend iRacing.
Personally, I enjoy a game that rewards "basic" racing techniques without requiring the same kind of concentration I needed back when I was doing this IRL. I just wanna have a few beers, talk to some friends, and pretend I'm actually racing again. The online part of doing this stuff is pretty important to me. And honestly..when the online is good, I still get a taste of the same kind of thrill I used to get when I raced IRL (DOH! That's the internet acronym, "in real life", and not Phony George's "Indy Racing League". )
I'll probably buy GT5 and a PS3 on the same day, when the thing comes out, just because I'm a sentimental old fool. But for the moment, FM3 does the trick for me.
I do find that a good wheel & pedals set makes things better (I did much better in GT4 with it than I'm doing in FM3 without it), even if you're just a "casual gamer".