I have GP3, Ubisoft's F1 Racing Championship (F1RC), and EA's F1
Championship Season 2000 (F1CS2K), and I would wholeheartedly
recommend F1CS2K as the closest thing to GPL in terms of modern F1
sims. I have a Duron 750 with a GeForce256 card, and F1CS2K runs
fine, so you should have no problems.
Check out the demo and see for yourself:
http://www.3dfiles.com/games/f1championshipseason2000.shtml
There is a TON of third-party support for F1CS2K, including a CART
conversion and a Trans Am conversion, and also an advanced physics
patch that I put together that really makes the physics come alive
(you can find that at the Blackhole Motorsports site, and I believe it
works fine with the demo).
The High Gear forum has a VERY active F1CS2K community, and there are
lots of helpful people there:
http://dynamic.gamespy.com/~hg/vbulletin/forumdisplay.php?s=&forumid=23
There is also an F1CS2K Rank site, much like the GPLRank:
http://f1cs2krank.dhs.org/
And also an active offline competition as well:
http://hem.spray.se/redeby/f1/offline.htm
Of the three current modern F1 sims, F1CS2K wins hands-down as far as
I'm concerned.
Enjoy!
-- JB