For me..... your problem is Vista! Just had to reload a laptop with Vista Home Basic. I had to use a seperate PC to download the correct drivers (yes, originally downloaded the wrong NIC driver).... but got things back up and working. Make sure you double check all your drivers (correct manufacturerer). Some PC Manufacturer use different manufacturers on their same model of PCs (There was 3 different manuf. for my laptops nic card)........Know what you have first! Mine wasn't easy, I couldn't just flip over and look and the manuf. stamp.
The backup (depending what you backup) will just backup the data, not all the programs themselves. Your correct, You will need to reload the programs (so, make sure you have all the program disks and lic keys). If it does backup everything (Operating system and all), then you will have the same problem....just on a larger drive.
To me, this would be a last resort. Have you already tried to clean things up first.
Sorry for the rambling.... I've been having PC issues lately and it's getting under my skin.