I have a bear drive, I call him Mr. Chocolate. Only joking.
A bare drive will come without cables, software and probably original packaging. If you have an 80pin IDE cable and an internet connection this should be no problem at all.
An OEM, or Original Equipment Manufacturer model will often be made by one company and rebranded by others (in the case of hardware at least; software OEM is not usualy rebranded but can have a different license or limitations). Often this is also sold without the cables and packaging and can often be a value added purchase.
Specificaly in this case if you were to buy, say, a bare philips or benq drive, it would still be their brand and firmware, as opposed to the likelihood of generic alternatives with an OEM drive. The internals still probably came out of the same factory, but you may have e.g. G7V9 as opposed to B7V9 f/w. Read round this great forum and you can patch that like I have. Thanks everyone.
edit: unless you are actually talking about a bare OEM drive? Back to OP.