Buy a new hard drive. They are cheap as chips, a 250Gb 2.5" Western Digital Scorpio will set you back about Ł60.00. Remember you need an IDE drive. New computers use SATA. Delay and you might not be able to source IDEs. Reinstall your programs. The system recovery disk makes things much simpler and you shouldn't have the embarassing telephone conversation with Microsoft to get it accredited. A clean install will run much better than any attempts to rescue programs.

Put the old disk in an external case - you can get these for as little as a fiver although post will double that. Copy your data across remembering to include your Outlook .pst file. The chuck the old drive - it just isn't worth the risk.