Originally Posted by RoryHe
can someone enlighten me between the differences between classes
higher number is faster?, i'm guessing
The class number roughly corresponds to the minimum write speed of the card, in megabytes/second. Thus a Class 4 writes at 4 MB/s, Class 6 writes at 6 MB/s, etc.
Class 4 should be sufficient for everyday use for most people, but obviously a faster class is more ideal, especially if you're downloading/copying ROMs and such to your card on a regular basis.