I'm happy with a Transcend 4GB. As people here have reported, a 4GB card works with H4.
If a file exceeds 2GB, the header is screwed up due to the firmware not supporting 4GB card,
so you need a little tweak with your PC, but as long as each file is less than 2GB, you can
record up to the full 4GB without any tweak. As people here suggested, you should only
format a 4GB card with your PC, not with H4, with the same reason.