Removing Worm/vb.zz in windows XP

My Windows XP PC is infected by Worm/vb.zz that converts .doc word documents to .src screensaver. After installing AVG, it cleans by deleting .src files and svchosts.exe. After restating, I can’t login again. How do I remove it without formatting and reinstalling my computer? John K. Tarus – Moi University, Kenya