Memory Cards for Dreamcast

[RedsunsFD]

I want to buy a memory card for my dreamcast: Should I buy the one from sxxa, which I think is very expensive or one from another firm? I came across one with 4 meg and it has also a cable to connect it with the pc so I can backup my save stats on my comp. Someone has experience with something like that?
I've heard the mem card from sxxa has 200 blocks: how many blocks do a game normally need (give some examples please)? Do I really need a big one or is a 1meg card already enough? What mem card do you recommend?