I had big problems with FNW from the start on. I tried everything: from the d3d fix to whatever was supposed to maybe work even reinstallation (also for steam). I couldnt play the game - whenever I went outside a house I had about 20 secs before it totally crashed to desktop. Inside houses it was no problem at all! The only thing I didnt try was totally shutting everything off: I dont have antialiasing or anisotropic filtering on (ZERO samples for both!!!) and I play the game in windows mode!! Since I did that I have played over 10 hours and liked the game very much even with the much reduced graphics!! I play it on 1920*1080 and everything set to very high! There was some crashes - 3-4 so far but that is something most users seem to have! So if you play in window mode you can expand the window that much so that it is just as big as your screen - so it's ok to play! The graphics are not the best at all and I hope for the patch to make my game run like it should be!
My system:
Win XP+Sp3
Geforce GTX280
newest nvidia driver

good luck for all of you - the game is great (and I play in hardcoe modus which I dont find too hardcoe...its more softcoe....) but the bugs and graphic issues are a mess!! Hopefully the developers will fix that with the next patch!

Yup, this worked for me too (GT 240). I have two tips to offer you might want to check out:

1) Using this tool http://www.newvegasnexus.com/downloads/file.php?id=35817 you can play the game using the full screen even it's in the "windowed mode" in the options;

2) You can turn on AF (I have it set to 4). But no AA!

With this setup I've played 25 hours already without A SINGLE CRASH. I turn AA on, or I turn full screen on, after 20 seconds I get a crash (outdoors or when loading a location).