http://www.f-secure.com/v-descs/brontok_n.shtml

Brontok is a complex e-mail worm. This particular variant was found at the end of March 2006. The worm spreads as an attachment to e-mail messages. It also disables anti-virus software, creates multiple copies of itself on a local hard disk, and takes efforts to make its removal difficult.

Given the complexity of this infection (major system files infected), your PC may never be the same (or be completely cleanable) unless you backup your critical user files and do a clean install. 121 virus infected files puts your PC in critical condition.

Post a HijackThis log (see procedures in my signature), if you want - and we can further confirm the above assessment or possibly get some limited functionality back.