Can anyone recommend a card? Or is this a bad time to get one, as Half Life 2 and Doom 3 will make anything I buy obsolete in three months?
Definitely a bad time to get one.
Wait a while. ATI's 9800 and X800 will come down and price, and you can get whichever gives you better price/performance then (I made the mistake of getting a 9700 pro about 3 weeks before ATI released the 9800).
As for Doom3, this is more reason to wait. Typically ATI has the better hardware, but it chokes to death on OpenGL. As an aside, I really dislike the way nVidia does business. ATI just announced they're rewriting their OpenGL drivers to stay competetive. If they do it well, they may just beat nVidia in that arena as well. Time will tell.