hi Peter,
Xp+ sp1 should work without problem , check wireless card drivers, r those updated, www.windowsupdate.com
Check Wireless One Configuration service is up, Which Access Points u r using, if wep keys are automatically getting provided (128 bit ), u just enter SSID of AP in wireless card & check ifit works for XP+ SP1, if u r using peap+ mschap v2,, use only Microsoft propritory PEAP supplicant, & do not enter cisco or other vendor supplicants,
That's my 1$