Windows 7 - windows.old folder and viruses

Just had a question that I thought was interesting lets say i got a virus today and reinstalled my windows seven tomorrow not useing a clean install would the virus then be moved to my windows.old folder? And would it be possible to just delete my windows old folder to get rid of it. This had not actually happened i dont have any viruses well i think i dont i need to get me some virus protection but thats a question for another day it was just something that popped up into my head. Thanks for all responses

Wipe your partition and unstall a clean OS.Why do you wante to keep old folder?

i dont know what you mean by"Wipe your partition and unstall a clean OS" Whats a partion and to answer your question i dont want to keep it i was asking if you had the windows old folder and there was a virus in it from the previous version of windows would it be deleted when you delete the windows old folder from the harddrive.

I mean that you have to format C: and install a new clean version!
If you remove the old version, the virus will also be deleted.