probable virus??

After stupidly letting my brother on my comp i have discovered my comp is now infected...OBVIOUSLY cos he was looking at stuff he shouldn't have and has no idea what he is doing anyway....

I ran my anti virus program which found and removed a number of infected files.
I ran Spybot S&D which also did its magic

But i still have a problem....on my desktop there is a html document apearing instead of my desktop background....the html doc seems to be oo top of the background. When clicking properties of the html doc it says it locatedn at file://C:\WINDOWS\desktop.html.
Ive tried looking for it to delete it but cant

Some help to get rid of this would be great

Stuart

PS - when trying to view this message as a preview my explorer just went to some gambling site....obviously i still have some virus issues??

SYSTEM
windows xp pro
128mb
40 gig
553 hz
AntiVir for virus program - always updated