Yah, you can.
In fact, I'm about to do it, using an MK6006GAH drive, but any drive ending in MKxx06, MKxx04, MKxx07 work with the H3xx series.
It's a simple upgrade really.
Just open up your iRiver, get the battery and blue padding and bottom metal brace outta the way, remove old HDD and insert new one, format it and Ta - Da, your done. Make sure you backup your old files by the way, to move it onto your new HDD.
