I HAVE A VIRUS

The worst kind to get. A computer virus. It really stinks. I guess there is this new one, that I had never heard of. A window comes on your computer telling you that you have a virus, and if you click here, then it will run a scan and clear your computer of everything. Well, when you click "here" to run the scan, it imbeds the virus in your computer. NICE. It is the XP ANTIVIRUS 2008. I have tried everything I can to get rid of it. The files to delete are hidden, it seems immune to any spyware detector. I am at the end of my rope here. If anyone knows anything and can help, or point me in a direction of someone who can help, it would be greatly appreciated. And, if you ever see this on your computer.....dont click HERE!!!!!!