Personal archaeology dig...

Dumb computer question (I think): I have an old computer tower and I want to see if I can get off an old information off of it. In order for that to happen, I just need to connect it to the monitor/keyboard/mouse and the power, right? Or am I missing some other vital connection? Should the flat screen have any troubles connecting? The old tower isn't XP, it's old Windoze 98. Is there any other way to get information off?