There's a good chance you'll need to replace the RAM battery; it's a standard CR2032 (the Duracell ones are called DL2032). It's the same type of battery used by the Dreamcast VMU (but thankfully lasts much longer in the Saturn). If the battery is dead the Saturn will still work, but the system settings and saved games will not be retained when you turn the power off.
Also, if you're interested in using CD-R games with it, there are two methods to boot them - a modboard or the swap trick. The swap trick is easier on Model 1 Saturn systems (oval power/reset buttons), and it's easier (i.e. possible) to find low-cost modboards for Model 2 Saturn systems (circular power/reset buttons).
There are Model 2 systems in Model 1 cases, but these are not very common, so just looking at the buttons is pretty effective, not to mention that a seller e.g. on ebay would probably be more willing to tell you the shape of the buttons than to open up the system and tell you what the PCB revision is 🙂.
Edit: Forgot something... it's a good idea to get an A/V cable with the Saturn. They can be found seperately, but are not as common as e.g. PSX or N64 cables.
Hope this helps.
(Edited by ExCyber at 1:53 pm on Nov. 4, 2001)