I smell grey market.
It sounds like NewEgg is buying product from an unauthorized source and they sell it to the customer without giving all the details. It's a common practice in all retail sectors, but with the tech stuff that needs warranty service it's particularly nasty.
Grey market isn't strictly illegal, it IS an OEM drive. NewEgg probably bought it and sold it as such. The problem is that their buyer got it from a dealer that is only supposed to sell that drive to a particular OEM, in this case Dell. And IBM is well within their rights to refuse warranty service because it was purchased through an unauthorized source. It really sucks though.
On the up side, most "reputable" vendors that know they sell grey market merchandise will cover it with their own warranty. They know they risk losing customers otherwise if word gets out about this shady practice. Some vendors even publicly acknowledge that they are grey market, and just tell the customer up front to come to them for service.
Steps to take:
1. Call NewEgg to see if they'll take care of the issue.
2. Call IBM back to tell them that NewEgg is selling Dell OEM equipment. (Assuming you didn't already.)
3. Call Dell to tell them that NewEgg is selling Dell OEM equipment.
4. Make a report with the Better Business Bureau.
5. Call your local Dept. of Trade and Consumer Protection office and file a complaint report.
Many people love NewEgg, and that's fine. But they DO have some funny business practices, and in this case you as a customer are paying the price. Hopefully they replace your drive, but even still youl been sold a product that is not a public OEM drive.