Which capacity faster on memory cards?

[ppower]

Im going to buy a microsd card for my touch but I wonder that if there is a difference between 2gb, 4gb and 8gb cards. Is there any difference on access times to big files for example, and also which brand is safe and fast?
Regards

[nmesisca]

Ask for what Category number the cards are. The higher the cat number, the higher the transfer rate of the card. There are cat 4, and 6 around at the moment. The larger the card, and the slower it generally is; I bought a 6GB card which only came in cat4 a while ago.. I believe you can find cat6 8GB now. Price also varies based on cat.
Good brand is Sandisk.

[urchinray]

I am using scandisk Cat4 8G, I find that very nice. I just only can compare with the original 1G scandisk. 8G much faster