so has the issue of ur wu not working been fixed? tia... i too have the betA SP2 which prevents me as well from getting to wu v.5 or v.4, or i may be a dumb arse for not rtfm... lol
bads U may want to try this as i did if ur still in the same boat:
I cleared my m$ cookies, deleted temp files including offline content, i re registerd urlmon.dll by entering the following in the run box " regsvr32 urlmon.dll "
i reset xpantispy to default system state, under ie6 system property's i cleared the "ssl state under the content tab" and then rebooted a couple of times... THEN I was able to get to the wu site and scan for updates succesfully... YAY!!!
BUTT the first critical update was a High Priority Update called
WINDOWS XP SP1 EXPRESS 
below that were
other critical updates from DEC 17, 2001 to APRIL 2002 so it's a "SP2 bug correct"?
Anyway google has a ton of websites dedicated to this XP 2055 betaSP2 wu tips.
anyone know sumting new on this subject... tia jiz.