That’s definitely still a highly usable computer. My primary computer is still a 1.33GHz PowerBook 12” because I like the form factor so much.
Some tips from my experience:
-You may have to give up the latest versions of software, most obviously MS Office 2008. Office 2004 is pretty snappy but 2008 is a dog. And if you run it with Mail, a web browser, then it gets completely bogged down. Stick to 2004.
-This doesn’t apply to Mac OS 10.5. Newer Mac OS X releases actually tend to get better on older hardware (assuming it’s supported, which your PB is). Install it!
-Get more RAM if you can – that’ll provide the greatest boost in system performance for you. But keep in mind it can’t be used in a new computer in the future.
-Make sure you have enough hard drive space free (at least 5GB, 10GB if possible). If you don’t the computer will have to ‘page’ more and that will also significantly reduce your performance.
-If you haven’t for 2–3 years, do a clean installation (backup your data, erase the HD, and install from system discs). It will once again help keep it snappy and minimize problems. If you’re going to Leopard 10.5 that’s a great time to do this.
In any case it’s not terribly fast but your PowerBook can run virtually all the software on the market today and thus has similar functionality, just not speed of a current computer.