how do i get my virus protection to let media center extenders through?

My whole desktop theme is black and says Warning Your Computer Has Spyware. I have a virus protection, but it states my computer is fine. How to get rid of this thing.

I have been having problems with spy-ware, spam and even viruses getting through my virus protection and firewall. Can anyone direct me where I might find free PC Maintenance tools? ie: registry cleaner, spyware, etc. Thanks so much!

My computer is very out of date and only has Windows 98 on it. I only use it for school but need to download some kind of Virus protection. I know nothing about them and could use some help.

I have a Gateway than runs on Windows Vista. But anything Microsoft 2007 I uninstalled just because I didn’t like it. I don’t know if any of that makes a difference or helps, but I’d really like some feedback about virus protection I can buy.