App2sd - Changing the SD Card
Yes, I did that myself, like this:


power the phone off and remove the old SD card
mount the old SD on a PC, copy its entire contents somewhere on your hard disk
mount the new SD card on a PC, format it as FAT or FAT32 (make sure it's the same file-system as the old one)
copy the contents of the old SD card onto the new one
insert the new SD card into the phone, power it on.