Computer locked down.

I am running windows xp pro sp3 on an HP Compaq dx2450mt computer.

I have been the receipent of a link to a virus/adware removel site that has locked my computer down. I can’t even get it to shut down. Does anyone know of any program for a computer elliterant operator that will remove these kinds of programs/links without crashing the rest of the installed programs? Please, help me!!!!