How to determine what product a microsoft product key goes to?

Hi:

I recently bought secondhand a Microsoft action pack binder from 2005. And in that binder were not only disks that seemed out of place (e.g. a windows server 2003 R2 disk 1 and a virtual PC 2005 on the same disk sleeve) but also just some CD sleeves with product key is without a disk. My question is is there any tool, method, or site that I can use on my own to punch in the product key and identify what it goes to? That I can avoid having to call Microsoft at all. I dont mind having to do that, but it would be nicer if I could just do it on my own.

Please note that the product key labels in question look like the following:

PRODUCT key:
XXXXX-XXXXX-XXXXX-XXXXX-XXXXX

Thus, the label doesnt tell me what product it goes with.

Well update:

By absolute sheer dumb luck, I was able to find at least products that the key will activate. All Microsoft discs have a part number on the inner ring before you get to the data surface in really tiny print and most of those keys had a part number. However matching these two part numbers didnt seem to work. So the answer here is sheer dumb luck. The keys were also so old that Microsoft couldnt even identify them.