I'd like to give my opinion about how I manage my windows system. feel free to leave your take on my methods.
firstly, I use windows 2000. I like the look of windows XP but it doesn't seem to like to be restored from a partition image. Probably due to copy protection. So I opted for windows 2000. Also, I don't bother with defragmenting, scandisk or any spyware removal programs. I've noticed that the performance of windows naturally degrades so reinstallation of windows (or restoring a main partition with a backed up image of that partition just after installing windows) is manditory, at least once a month, ifnot more. To fascilitate this, i've partitioned my harddrive so that it acts as two. on the main drive, i install windows and then try to keep all extra things on the second drive, especially programs that need to be installed. of course i install antivirus software and use firefox. in my experience, most viruses and spyware have forced themselves onto my computer through internet explorer, thats why i've opted to use firefox instead.
the reason that i don't bother with defragmenting, scandisk or any spyware removal programs is because they aren't absolute solutions. you'll never completely remove spyware once its on your system, nor will defragmenting or scandisk keep your pc running like it was just after installing windows.
another good point is that restoring a partition from a partition image may be much faster than running the windows installation process, depending on the size of the partition.
if i had the aplitude for Linux to enable me to use it well with my notebook, i'd have dropped windows a long time ago.
software i use:
AVG antivirus Free edition http://www.grisoft.com/doc/40/lng/ww
partition saving http://www.partition-saving.com/
unltimate boot CD http://www.ultimatebootcd.com/