Wirelless Connection SLOW

hi. In my lab we need to use a wirelles connection beteween 2 pcs. After installing those D-Link (54Mbits/sec) cards, the connection was unbelievable slow (by average less than 1Mb/sec). The 1st pc has XP and the other win2K.
After using 2 pcs with win2K, both, the card seemed to work really faster. Why?

do you have all the latest updates for both platforms, including drivers for the network adapter?

if so, check your firewall settings

beyond that, I'd say look into physical interference, perhaps remove the network and set it up again in windows, maybe you messed up a setting. good luck.