Removable drive not seen

I bought one of those USB adapters that allow you to use internal hard drives as removable storage. It has been working well until today. I repartitioned and reformatted my 80 GB hard drive to use as storage and tried to plug it in using the adapter, but my computer isn’t seeing it. I’m using WinXP SP2. WHen you reformat does it automatically assign that drive the c: designation? If so, how do I change it? I’ve read all about changing drive letters, but that doesn’t help if I can’t see it in the first place.

Please help! I’m beginning to get that funny feeling you get just before something bad happens (in this case, my hard drive crashing).

Thank you in advance