<< I bought a Gameshark Massive memory card, 16x and includes a cable to up/download to a pc, $20 at an EB. >>
This is the only memory card I've ever had problems with (I own several 200 and 800 block cards). While playing games, I'd often get an error that would say: Memory Card Not Found (or something like that, I returned the memory card shortly after I bought it in December). Another gripe I had with it is that the software for transfering your save games to your pc is only compatible with Win95-Me. No 2000 or XP compatibility.
It sounds like a good deal for the money, but that error would screw up games and I couldn't save. After reading the forums at gameshark's website, it seemed like that was a common problem and most people were unhappy with them, so I'd advise staying away from it or returning it if you can.