windows anti virus pro

Hi Everyone.
This is my first post and I hope someone can help me. This thing has pretty much taken over my pc. It will let me go online (but keeps popping up) but it won't let me open any of my programs. I am not very computer savy so if something I say doesn't sound right, ask and I'll try to explain better. When I click something, say my mailing list, I get a balloon that says it is impossible to run this program because it is infected. I can go to my control panel, but it won't let me open "add and remove." I have gone to several sites that say they can help me remove this thing but so far, no luck.

You will have to walk me through this step by step because I am old, slow and have ADHD. I'm kidding. Sort of.
Thanks,
Trisha