[Publius6961]

I will go to Sam's Club
Ditto.

I may be wrong, but at least in California, Costco cards are valid at Sam's club, which leads me to believe that they both inhabit the same corporate umbrella...

[Solson]

Not at all. Sam's Club is one banner under the Wal-Mart corporation. Costco is its own company which competes directly against Sam's Club. Sam's probably made Costco cards acceptable so they could drive Costco customers into Sam's without having to charge a membership fee. Smart move on Wal-mart's part.