Class 10 is pretty much overkill, will cost far more than a regular card and it wont give you that much extra if you just use it for normal activities.
I have a Sandisk 16GB Class 4 card and it works outstanding.
Keep in mind the Class 4 mostly refers to the WRITE speed, the READ speed greatly exceeds the "maximum" of 4.
Run a benchmark and you will see

I always go for Sandisk for memory cards though. They simply seem to perform the best.
Though Kingston makes very good card as well they just... Not quite get to the performance I get with Sandisk.
Ordered mine from opus.de, it's a European supplier.