Reformatted my hard disk and reinstalled Windows XP. Along with mIRC, BitTornado, Firefox, Thunderbird, Spyware S&D, AdAware, Acrobat Reader, AVG Anti-Virus, QuickTime, Real Player, Media Player Classic.
Lost my Firefox bookmarksdue to carelessness. :( Oh well, have to rebuild it from scratch.
Critical parts of the system are up and running (firewall, updates, anti-virus, anti-spyware, drivers). I believe it's time to say mission accomplished.