I have two questions that would clear this issue up for me to go ahead and buy cards

1 SD v SDHC - is the HC "high capacity"? I thought that related to the above 2GB side of things - what is the difference then?

2 "working" - I really don't care at the moment if I buy a 4gb that only works to 2gb capacity but then will work as 4 with a future OS upgrade, what I want to know if that it will work at all?

cheers.