hello mate,
don't think brand matters much tbh.
I use a 2GB card - it has to be FAT formatted on your PC first.
I believe HDSC cards need to be FAT32 formatted, but I am not sure if they will work on early version units or not.
i-tunes music format does not work so I convert all my files to MP3. Best way to convert is to right click on the album in i-tunes and convert to MP3. You then need to drag and drop the MP3 file off your "My Music" folder onto the SD card. Takes a bit of time to do, but it is worth it.
I don't think video works at all off the SD card, only directly from the built in DVD drive.
hope this helps.