Aim Virus Messing Around With My C:\windows Folder

Okay, so I was talking to my friend on IM yesterday and then she sends me a message saying OMFG LOOK AT HER or something like that and then a link. I stupidly opened it and then two seconds later she IMs me telling me not to cause it seems to be a virus. Usually I don't accept those kind of things but it was from her so I let my guard down. Apparently she had got it from another one of her friends.

It's a .pif virus I know that much but it doesn't do much, I can still open AIM and my task manager with no weird things but when I reboot my computer, my C:\WINDOWS folder pops up at the startup for no reason at all. Then when I x out of the window, I can't find that system folder anymore but according to Norton and Spybot, the folder isn't missing. I rebooted again and saw nothing really missing but I don't know. Anything to do with that folder makes me paranoid. Help me please?