I had a similar problem a couple of weeks back. My enemy went by the name of AntivirusSoft, and it was a bitch... At first, anyway. But once you know how to get rid of it, it's relatively simple to deal with. So, here's what you do~:

When you turn on your computer, push the F8 key repeatedly and start your PC in Safe Mode with Networking. Open Internet explorer, click Tools and then Internet Options. Click on Connections and then LAN Settings. Uncheck the box that says "Proxy Server" and click on Okay. You should be able to browse the web without it redirecting you to the bogus sales site now.

Next thing you should do is download Spyware Doctor, a free Spyware detection program. Let it scan your computer and you should know what you're up against within a couple of hours. Once the scan has finished, it will offer to remove the programs if you buy the full version of the program. You can do this if you want to, but you can remove the files yourself if you have enough patience.

If you opt to remove the files manually, this is what you do~: Click on My Computer, Local Drive (C drive~) and then Program Files. Search for the folder/s that bare the same name as your infection and delete 'em. But be warned, deleting the whole thing at once isn't possible. You have to delete the components of the folder separately, which will take an hour or two. Once you've removed the file, check around your C drive for any other rogue elements that might have spawned up. Once you've done this, set your computer back a week using System Restore and the problem should be gone. And if that doesn't work, take your PC to the local tech store and pay them to remove it for you (Average cost is under $80).

Simple, huh~?

Yoji~