I would expect it to work with any 1.3 rom.
IIRC, the stock rom was only compatible with 1.3. TJLazer (frequents this site) sells an updated rom for the 500XP. I believe it will allow OS3.1, larger hard drives, and removable media. He can tell you more.
I have a 500XP that will be partnered with a Turbo28 when I have space to set up the system.
