New Exchange 5.5 Server

Hey all, my office is looking to set up a second Exchange 5.5 server (just until we get a chance to upgrade the entire network to 2k3).
From the looks of it, this should be starightforward, install a second instance of 5.5 of another server (same domain), and have it join the existing site. Directory syncronization should keep the two mirrored (relativly).
Are there any major pitfalls I should be watching for here? Some glaring problem with setting up the second server that I’ve overlooked?

Any input is welcom, thanks!
Travis