How do I know this?
Well, I installed a program which told me large driver support wasn't fully enabled, so I let it enable it and reboot, once it did my 500gig drive was there, all data in one piece and everything ready to rock and roll...
Balls.. probably means I didn't need to lose any data after all
As I haven't done anything over the top to either drive as yet I'm gonna see if I can recover my two 250gig drives, although I fear the formats they went thru and partion deletions could make it a problem.
Still, this is a win really, as I thought I'd lost 500gig of data.. turns out its ok after all, shame about the rest of the stuff but well, thats life I guess, mistakes are made and things are learnt [smile]