How do I get rid of this pesky virus?

It keeps downloading error cleaner, spyware protection and turning my desktop background red with a nuclear symbol on it. I downloaded Smitfraud and used it and the virus goes away for about a day or 2 and returns. Super anti spyware helps, but if I turn off my computer the viruses go to town taking over my homepage and background. What the heck do I do? If Smitfraud cant fix, what do I do?

How do I get rid of this pesky virus?anti virus protection

Heres what you should do now, and later on for cleaning out your computer.

A short Introduction:

Many people have various issues with their computer - it's running too slowly, games aren't working, pop-ups appearing out of nowhere, internet connection going to the dogs, etc. But where many people go wrong is having too much trust in themselves and their PC - people think "Oh nothing bad will ever happen to me" and also largely think "A PC can take care of itself". It will happen, and your PC can't.

The following steps are things that may seriously help your PC out, and anyone who has never done these things before should do it - be aware that a lot of this is largely directed at Windows XP Professional %26 Windows 2000 Professional, but anyone with a Windows machine can use most of the advice in here (just some menu options etc. may be slightly different).