Will XP reload be affected by virus/worm/other infection?

Hi - first post, and I'm a bit of a novice so I'll be going slow...

I have a laptop running Windows XP Pro SP3 which has picked up a few bugs recently and although I've gotten rid of most, its running very slow. The most recent is a Win32 Generic Error bug that I can't seem to find a solution to and is driving me nuts. I'm wondering if reinstalling XP is the easiest way to get my PC back to something like rude health.

I've got the original disks, which I could insert into the CD drive and presumably would auto-install and over-write whatever's already on the hard drive.

Alternatively I've got a copy of the system from about 6 weeks ago stored on an external hard drive that plugs into the USB. My concern here is (a) if I plug the external into the potentially-infected PC am I going to infect that drive also, and (b) the Win32 bug has caused problems with accessing the USB ports.

There's nothing on the PC that I can't reload from other media, and it doesn't take long to reload antivirus and other add-ons.

Is reloading a good idea, or am I talking out of my hat?

Cheers

 

Thanks PeteC - like the set up you've got here

All noted, thanks, and appropriate post made in M&VR Forum.

Cheers