Thanks for your replies.
This is actually driving me crazy, and whilst the advice regarding a factory reset is good and obvious advice, I'm loath to do it because I would then lose everything i've worked so god damned hard to incorporate on my phone.
To give you an idea of the lengths i've been to i actually reinstalled Windows 7 fresh and installed the driver from HTC and it connected....for about 3 mins. It then vansihed and i'm back to square one, and the elusive driver is nowhere to be found, although the HTC uninstall device is easily located.
I know the cable from phone to laptop works because the phone charges, and i know the driver will work once installed because it did actually work for the three mins i mentioned, when i did actually manage to transfer a test video from computer to phone with no issues.
The other interesting thing is this: When I tried to bypass HTC and install PDANET the set up screen gets to 'installing driver' and just sits there and does nothing, I actually left it for two hours and it didn't move from the 'installing drivers' message.
With that evidence, I beleive this is an issue with Windows 7 either allowing the drivers or accepting the drivers.
The other thing that occured to me was: Could I get over this problem by enabling my computer with a bluetooth dongle and simply transfering files that way? I was wondering if bluetooth connection and cable connection were one and the same thing, albeit over a different platform.