I didn't bother reading the rest of this thread, but it could be the USB drive itself or even the USB cable that's causing the problem. I had a 120GB Western Digital Passport external drive, and thought all mini-USB cables were the same, so used my USB cable for my digital camera. Well, OSX wouldn't recognize it, and in Vista, it failed more than half the times. Often times i would literally need to hold the drive at a certain angle for it to be recognized. And after awhile, it'll fail and i'l hear ticking on the drive. I thought it was a bad drive first, but then found a 2nd drive doing the exact same thing, and this drive was brand new. Once i used the cable that came with the new drive, it was working perfectly. And when i used that cable on my old drive i thought was dead, it worked perfectly, even in OSX which it NEVER did.
I hear this is because some USB ports aren't providing enough power to the drive (the WD site sells USB cables with double connectors to power the drive in systems with low powered USB ports). And I'm assuming my digital camera USB cable was probably limiting the amount of power it could handle.