|A bit more information would be useful?|
Can you see the wifi network/access-point in W2K; and actually see/identify its SSID
Have you control over wifi security settings; mac-access list; WEP/WPA options?
Is the wifi card/adapter usb or actually internally installed? If internal which slot in motherboard is it in? If it's in the one immediately adjacent (next) to the agp slot... then move it to another psoition. Those two slots share the same irq and typically network cards won't work well (if at all) in that position if agp slot is also in use...