How do I deal with Yahoo Messenger viruses?

This virus changes my status into some sort of Thai thing, then sends this link to all my contacts. I've read that I have to delete the files SSCVIIIHOST and SSCVS, then reboot. I've tried it, but doesn't work. Follow-up, are there any good free antivirus or antispywares out there that doesn't really cause any detrimental effects to my laptop? Please, I'm begging someone to help me. I feel so helpless.