I have more or less given up on my SD card blues. At the moment I have an old Lexar, Speed class 2, External SD-HC card of 4 GB capacity and the original 2 GB internal one. That works fine.
In my opinion/experiece, the IQ aparently destroys SD cards, whatever way: bad power supply, bad internal timing or ...
As I told above I tried 2 times a 4 GB class6 cards of Transcend, both were wrecked.
All my docs are on the external card. With Android 2.0.6 you ave plenty of space to install whatever you want on the internal card.
A good designed operating system (haha!) can check the speed class of the card and adapt it's Read/Write speed to it.
Just suppose the IQ does this ;-)
-- You install a class 6 card, then the IQ uses high speed transfers, but maybe to fast for the rest of the hardware.... poof... problems with the card.
You (read : I ) installed a class 2 card, the IQ uses low speed transfers, but the rest of the hadware keeps up wit this speed..
How does that sound ?
Of course I'm just guessing.
All the best. Tom