Well usually I'd say "if it ain't broke, don't fix it" but at some point you're going to need/want an update, and SP1 is going to be a prerequisite for that.
As to whether you want to wait to do it until you HAVE TO, well that's up to you. My advice might change for example if I know your PC was a "travelling business laptop" or otherwise susceptible to security issues. In general though you want your PC to be up-to-date, and SP1 has been out since Feb so it's not a risky thing to install.