Sorry to bump this old-ass thread. I just wanted to report my findings so nobody else makes this same mistake:
The A-Data 4gb CF card is what I purchased from New Egg. This was something like $17 shipped. I know, I couldn't believe it either.
Well, sad to say, it doesn't work that well. It seems to be tempermental in cold climates. Both myself and Bilzfan have found that this card will cause problems when it's cold. Once it warms up, it seems to work fine...
For more info and/or symptoms, please see my first post in this thread:
OEM Navi Card reader question
Anyway, just a heads up to those who do not live in relatively warm climates. I made the mistake of buying this card thinking I was getting a great deal... Unfortunately, this is not the case.
Popinjay, if you want to add that to your OP, that'd be cool too...