Why would you want the original rom version?
Anyway here is a link to the A00 rom
http://support.dell.com/support/down...&fileid=105732 . You aren't able to downgrade the rom from your desktop -- the flash utility won't allow it. You have to copy the rom to an SD card. Use the img file with _C_ if your device has wifi and bluetooth or _N_ if it doesn't. When you have it copied you hold in the scroll wheel and the contacts button and hit reset. The flash should begin right away.
I would recommend _not_ going to A00.