Does Windows XP SP3 have any serious effect on the game programming?Or does anyone know?Because before,I was playing Nexuiz just fine(But I had to quit because the upgrade was taking so much of my LAN) but whenever I try to launch it again,I find all of the servers pings above 400 and it's slow even on the menus and in campaign games.

BTW,I always use it on the lowest settings possible(Except for the Game Sound)

Maybe the update busted your video drivers? I see no other reason why the menu should be terribly slow..
But then again MS record of updates includes a huge list of updates gone wrong

Windows upgrades... building quality on top of quality.

Well then shit

Got any advice on how to fix the vid drivers?

Start with the "usual" fix - (re)install the latest drivers from the GPU manufacturer.

And if re-installing doesn't work. Try some older ones.

No it shouldn't have a negative effect. I'm running XP SP3 and I've noticed higher frame rates over SP2. That is also what all of the gaming/computer sites are reporting.

BTW my system is:

Core2Duo E4300 with slight overclock
2 gigs ram
GeForce 7600GT
320 gig HD

On the "high" setting I get around 200 FPS for most maps. I'm REALLY happy with SP3...it's definitely more stable and faster than SP2.

This guy is talking about PING over 400. This just can't be a graphics driver issue! I think the SP installation smashed something else, like his NIC drivers or maybe firewall settings. So I advise to look for changes or problems there.

Any other online games you play? If yes, are they affected as well?

I have Windows XP Media Center SP3 and so far everything always worked correctly for me just like in SP2 with the game. It could be a configuration issue of sorts... SP3 may be incompatible with some SP2 things but from what I seen Nexuiz shouldn't be the case (though I don't know on the programming part).