One step less extreme that dumping the computer?

My computer has started seriously playing up, crashing, blue screen of death etc. I suspect Malware and someone is currently very kindly helping me to identify and remove.

However this is taking a while, it has been 3 weeks so far, it is not obviously any closer to being resolved, and I can't live without my computer, I need it for work.

So whilst I would rather solve the problem with some kind online help and downloaded freeware, I am about one week away from being forced to go out and buy a new computer.

My question is: Since I am considering the nuclear option of giving up and buying a new computer, are there any slightly less extreme solutions I should be considering first?

• Buy and install a new OS (it currently has Vista, I could upgrade to W7)?
• Format the internal hard drive, buy and install a new OS?
• Buy an new internal hard drive, buy and install a new OS?

And a related question: I have a few USB connected external hard drives I use for storing data. I don't store or run any programmes from them, just data files (.jpg, .doc, .wmv, .xls, mp3, mpf etc.). I would also ideally like to copy some data off the internal hard drive onto these external hard drives before wiping the internal hard drive.

• Am I just going to reinfect my new/refreshed computer as soon as I plug in these external hard drives
• Is there anything I can do to check that they are safe before plugging them into a new machine?

In case it was not clear from the above, I am very grateful for the help I am already receiving in trying to fix my computer, and my need to move faster is not a criticism. But my personal situation means I need to move fast, so I would also like some help on a plan B.