Q: Cleanup virus

Your problem is not due to a virus (or any other kind of malware) or temp files. That's Windows thinking, and not applicable to a Mac.

For some possible solutions, see my Mac Performance Guide.

In addition to Thomas's post, see:

Mac Maintenance Quick Assist,
Mac OS X speed FAQ,
Speeding up Macs,
How to Speed up Macs,
Macintosh OS X Routine Maintenance,
Mac troubleshooting: What to do when your computer is too slow,
Essential Mac Maintenance: Get set up,
Essential Mac Maintenance: Rev up your routines,
Maintaining OS X, 
Five Mac maintenance myths and
Myths of required versus not required maintenance for Mac OS X for information.