Problems with a D-link wireless card..

Hello.

I'm having trouble with a D-link wireless network card (DWL-G520) on my newly acquired computer. The machine is with a MSI socket-A motherboard(KT6-delta) and some 1,5Ghz processor. I'm running windows XP.
The problem with the card is that it works only like 0,1% of the full capacity(I'm not kidding here). I might be able to load one webpage and then the connection usually disappears. Also having the card enabled in the system manager usually bogs the system down somehow(everything starts to lag). Also sometimes when I activate the card from windows(if it has been disabled), the machine just jams and reboots. I've used the card on my previous computer without any problems and I just tried it and it still works.. I'm at loss here. What to do?

J