Looks like they released Service Pack 2 for Microsoft Project 2003 (including standard, pro and server).
In my experience Project Service Packs always fix more things than they break so the odds are good that you should just download and install it. This is not always the case with Windows Service Releases.
If you are wary, then check out the list of fixes and decide if it is worth it to you. With a list of 145 fixes (and a number of undocumented ones as well) you should be able to find at least one compelling reason.