One note about external microSD usage: Some flash cards has an internal knowledge of FAT files system and mkfs it with ext3 creates a huge performance problem. At least I met this situation once with 32GB USB stick - it was a definitely the formatting issue.

I guess, it is a reason why A-DATA sells a different 16GB SDHC for Eee PC and a regular for photo gadgets (see on newegg). I didn't test it.