Wow! What a difference in my cards.
External
Patriot 8GB class 4
2.46MB/s

Internal
PNY 8GB class 4
5.0MB/s

Notice that they are both Class 4 cards. So what's with the speed difference? Could it be fragmentation (on that small a card?). My internal doesn't get used nearly as much as my external, but it does have more of the space used, 80% vs. 55%.