The only one you hear repeated problems with is the 45GB version.
It's actually a little more than 45Gig, it's a 3 platter drive, and the platters are actually a bit more than 15gig...around 15.3 I think.
My 30 gig is actually 30.7, and the 45gig is actually 46.1 on the labels.
There is no 45gig 60gxp, just 20, 40 and 60.
Oh and the model number for the 45gig 75gxp is DTLA-307045
You can check that out, the model number for the 60gxp is really weird...