Yeah, Mem Cards are fun, especially if you rig up your own... and then you can dupe the data for backup =)
BTW, the cards are classed 59 - 256 - 512 - 1019
But people just call em, normal, x4, x8, x16 (even though it's not truely so =))
Also, the GC's 59 MEM Cards are 4 Megs each so in MBs, 4, 16, 32, 64