there is a very easy solution to that...
make an image of your windows partition (or entire disk if you want and have separate disk where to put the image).
When you got infected by virus and other silly things simply reboot machine and put a bootable dvd or something you made with the imaging program (remember Norton Ghost ?), then locate the image file(s) and make the program rebuild all partition or disk.
It's like when you restore machine at factory settings (e.g. just windows and some utility but not all your programs and data), but you can create an image whenever you want... after you create a "clean" environment and installed anything you like.
I used for many years Acronis imaging programs with excelent results always... can do network images/backups and load directly from another machine... or from even a corporate internet server... over a vpn tunneling... whatever!
Also you can store images in a separate e.g. usb drive... e.g. 500 gigabytes space... you connect it, run acronis and on the fly restore the image you want...
Today you need several tens gigabytes for a simple image of a windows machine... but it's not big issue, cause you have 1terabyte hard disks for cheap, usually people have more than one machine and effectively using network images you can put an image on another computer of your network etc...
all very easy.
So, my advice is: get Acronis 2010 right now... and stop this annoying waste of time with windows restore and reinstall each time!
http://www.acronis.com/enterprise/
look for true image software , 2010 version is the last one
Kind regards,
Max