Will my computer work if i back up the drive, reinstall windows, and replace select files?

I'm tired of trying to fix that darn computer. I'm getting close to giving up on sytem mechanic and instead I'll reinstall windows on that infernal contraption. So my question is (and if it is possible, I'll shout for joy) can backing up the c drive to the external hard drive (that is programmed for disc back up) and then after reinstalling windows, will i be able to put programs like microsoft office and antivirus programs back with no problem? This is the ultimate question and I must know!!! Help!!!!