so much garbage out there about SD cards...
guys, forget class. first of all, the slower transfer speed is fir uploading to the card...not reading the card. and second, with regard to any smart phone out there, it still is more than adequate. i have a 16GB class 2 in mg classic droid. its plays all my videos...including The Hangover bluray (720p) without the slightest problem. its when your backing up orloading on yohr computer thats a problem...took me like 3 hours to fully back it up last week!
Class also refers to the write speed of the card. I am a videographer, and I use Panasonic HMC prosumer series cameras. These cameras (just like Sony and Canon) require class 4 or higher SDHC cards to be able to record HD (both 720 and 1080) video. Class 2 does not work because the write speed of the card is not fast enough. Now, that is recording AVCHD, and I have no idea what codec and container the Droid X uses, but my conscious tells me before I go spend money on a class 2 32GB card I would want to know that the card is capable to record 720p/30. Just throwing this out there.