if i flash my os to 2007 he what will be the biggest memory card i can use?
and is it enogh to flash the os or do i need to flash anything else?
thanks

I don't think the RS-MMC cards were ever made any bigger than 2GB.
I've personally never seen an RS-MMC bigger than 1GB though. The form factor has been long abandoned. Any available cards are going to be used or no-names.

I have a 1GB and best I could find a couple of years ago at a reasonable price was 512MB Sandisks. Still have a couple brand new.

Anything over 4GB would be SDHC anyway and unlikely supported by the hardware, even if you managed to modify a regular full size card.

I use 8GB sdhc in my n770 (wsod'ed).
I removed card lock door, bypassed the card switch and pushed full SD-size to microSD converter.
It works ok. I use whole space on the card (ie downloading 7GB torrents via aria2c downloader).
What is quite strange. I used my n770 without any card for a while and I've got some reboot issues. Since I've put my new 8GB card - reboots dissapeared.
It's crucial not to make swap on the card in my device since if the torrent downloader takes more memory some heavy swapping occurs. Swapping and additional communication to the same card made my os freezed for some periods - the result was occasional 32k watchdog resets.
Of course I use Fanoush's sdhc enhanced kernel.

The biggest MMC is 2 gig. Hard to find. I use 2 gig in my 770's with OS 2007 OS.
I think 8 gig cards work in SDHC though and 16 gig.