Nem if you use the software in the link i gave you (in your pc thread) then you can save a snapshot of your system after a fresh format. Then reformatting takes about half an hour (plus backup time) as opposed to half a day.
My work computer i had to rollback (=reformat) about a month ago, that was the first time in 18 months but that's because i buggered it up trying to get Intel fortran + microsoft's C++ and sdk to work with some finite element software (honestly, microsoft can't write anything that works).
On my home computer i haven't had to reformat in 2 years (i use opera). I run nod32, etrust spyware guard, pcbugdoctor (it works and doesn't delete things you actually need) and o&o defrag. No problems.
What link? I cannae remember

The amount of shit you get from downloading torrents and re-installing means I like to reformat every 6months for Optimum Performance. (maybe I'm wrong in doing this)
I use Diskeeper Premier Professional for defrag.
Can I ask why you use Opera? I did use it for a while but it is very buggy.