I usually clean the virus from my friends' windows machine by booting their machine to a Live Linux CD and removing the hidden viruses. Now a days the virus I see is a autorun.inf in every drive (which will have a line to the actual virus/worm/trojan). These may be hidden from windows, but crystal clear from a Linux.
You just need to remove the autorun.inf and the virus it refers too. Then run msconfig and uncheck all of them. If you know good enough about registry, remove the entries from it too. Otherwise don't touch them. These steps are risky, unless you know what you are doing.
If the above seems confusing to you, move to Linux and enjoy a virus free world.

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