Wireless Gaming Issues

is wireless streaming 3D video supported for a wireless network? i have a Linksys WRT-54G wireless router to use with my cable connection and i just bought an ati radeon 9200 128mb card, but i dont think it's that cuz it works fine in single player mode. i'm also using a D-Link DWL-G120 wireless USB card for my desktop ....when i try to play multiplayer 3D games i either get, in C&C Renegade, stuttering or extreme lag if that's what it is, about 20 minutes into playing the game. and it doesn't go away. then i downloaded battlefield 1942 multiplayer demo and i get the lag right away and a message blinks "Connection Problems!" or something like that and i can't even start playing the game after the level loads. but my card is only like 12 feet from my router and it's almost an open area connection (little interference or obstruction). so is it that my wireless setup can't support streaming video or is it some other setup problem? any help would be greatly appreciated.

oh and both my card and router are setup for G-only connection.

and actually all the network gear and internet was bought the same week so i couldn't tell you if it was my card or not. and would i stand to benefit from a new netgear 108mbps g-network router instead? (i now realize from reviews this linksys is much slower) and perhaps a pci nic for greater bandwidth and signal strength? (D-Link caps at 60%, even when i place my router and card 5 feet apart :|)