I hope there will be a reply to this question:
So I'm in good old South Africa (Southern part of Africa)
I have a:
P4 2.8ghz
1gig DDR400
80 gig Harddrive
Geforce Nvidia 7600 GS XFX (I bought this card as my 5600 FX ran the game but on low and most maps ran fine just some maps it stuggled, so I wanted a card that could play the game on low perfectly and now problems) - bought the card and on that day it ran everything on high no problems ))))
Next day the card turned around and told me it was sick...basically I couldn't even play the game on low.
Now I'm talking about online playing...
I couldn't run I couldn't get a proper shot off!!!
I've uninstalled and re-installed.
Re-installed the updated patch.
Defragged the PC.
Closed background programs
Close the anti-virus.
: ((( I'm think about getting 2 gigs for the board...
I aint looking @ upgrading as in South Africa it's an arm and a leg to upgrade.

Check your firewall, make sure you're not blocking traffic, check your drivers and make sure you're on a stable version for BF2 (google probably would be your best bet, I'm not sure if sites still have recommended driver lists for games)

http://www.nvidia.com
http://www.evenbalance.com

If your firewall reacts and starts blocking traffic because it thinks a virus has come you wont be able to get any decent action. It sounds more like a traffic problem though than a driver problem with the card. If you can play single player mode without much trouble then that would probably be the case.