Yeah, it's PCI Express on the mobo, but it's obvious why it won't fit...
The card had 2 notches in it and 3 sections of pins. The board has space for 1 notch.
The pin lay out on the side of the card closest to the bracket (the name for that mettle thing you were talking about) is long, but on the mobo it's short. The pin layout can not match...
You've got to get back to a best buy with the gift receipt or some form of proof of purchase and do an exchange. Time is also of the essence, as most stored have a time limited exchange period, be it 10 days, a month, whatever. The specific period in which you're allowed to return it, should be available on the receipt, and possibly online at their website:
http://www.bestbuy.com
I did a search, but the results are in a javascript session, and so might expire (require a new search from you) at some time:
http://www.bestbuy.com/site/olspage...7&entryURLID=cat12085&entryURLType=page&h=303
What you're interested in, is their return policy. There is no way to make that card play with your motherboard. The slot interface for the thing is just wrong for it...
What's likely is that your mother didn't know, and so didn't ask the right questions at BB; at which point the sales guy (who might or might not know any better) picked up on the wrong idea, and handed her the box for an AGP card...