Argh! I had one of these and it was a pain to remove. People who have the time to sit and write these things seriously need to get a grip.
I recommend that you download Spybot Search & Destroy. Just google it, it's usually the first result. Run the download and go through the setup process. When you've got the software sorted and installed, perform a scan.
On the note that you can't download things, try downloading some anti-virus software from another computer and install it to an external hard drive, or USB flash drive.
These virus's can be deadly so don't leave it too long. Back-up your most important documents to be safe. Don't go searching through google for anti-malware software because there's a pretty well-known virus lurking about which goes by a similar name.
I hope you get your problem sorted soon. OH and by the way, if you know the name of the virus you can search your computer for it, try searching the registry: Start>Run>Regedit. If you can't delete the file, but know the location then run command prompt: Start>Run>CMD and then type 'CD', from there type your file location eg:
cd c: \ Documents and Settings \ My Documents \ deadly file
When you've entered the location of the file type in 'del', that should force delete the virus.
When you've done that I recommend that you go download some anti-virus software immediately, something that is known, like AVG (I use that). Avast is also good, but the voice is sooo annoying when the software updates.
Hope you get your computer sorted soon, good luck!