Hi Jacked Browser

I have a machine that has been Hi jacked. It is a Gateway running WinMe, I know, dump Me.
There is a spy ware and invasion that has happened through the neglagent use of this machine by my grand daughter.
There is something called Spy Sherrif and cool web sites that has taken over the mahine. I have run Adaware, and SpyBot search and distroy in safe mode, yet Spy Sherriff keeps coming back.
Any suggestions?
I only have 50 pts left so thats all I can offer.