Trojan - I can't install or run antivirus

Hi everybody

I got an EeePC with Windows XP, but it has been infected by the recycler virus. Since then, I can’t install an antivirus or, if I can, it does not allow me to run it. I’ve plenty of them. I could install, but not run, Norton and PCTools Spyware Doctor. I couldn’t download the proper databases. I could install and run Kaspersky’s Virus Removal Tool, but it didn’t detect the Recycler.
I can’t even download Avast, AVG, Microsoft and many other tools.
Everytime I start the computer, a message appears on the screen “Surabaya in my birthday”… “Sorry I’m using your computer to send messages” and a lot of things in a language I don’t know. I can’t start the computer if I don’t click “Accept” to this message, but I suspect it blocks my access to diversal software and refrain me to download or run antivirus.
What can I do?
Thank you very much.

Talita

Have you tried Malwarebytes ?

Malwarebytes Anti-Malware 1.46 http://filehippo.com/download_malwarebytes_anti_malware/
always run update before you scan so you have the latest database
click the remove selected button to quarantine anything found
you may post the scan log here

I think you may have the Drowor file infector.

I suggest you download Dr. Web LiveCD from a non-infected computer and burn it onto a CD using ISO Burner.

Be sure you update Dr. Web LiveCD and let it disinfect your system files.