From the information you listed it is inpossible to tell, they are likely both dirt cheap and slow. But....
The only time you are going to see a difference is if you put the card into a converter and use the card reader in your computer. I do this as transferring 8 gigs of stuff can take a while. An 8 gig class 6 is only $19 at amazon, good deal IMHO.
I have the curve 8900. I love it but did not realize that I cant do videos without a card. How many pictures does the 8G hold? How long of a video will that do?
thanks