Static to DHCP ip configuration

We are currently using ip phones and some pc's in our office, the other tech guy who did the set up is luckily in the middle east right now and left me a brain swelling problem. We are using win2003 server standard edition and the other pc's are running in xp. Im a newbie IT guy coz I came from desktop publishing so this world is a really new one to me. As of now there's no problem about the ip addresses or ip conflicts but sooner we are planning to add some more. I hope you guys can help me. Thanks a lot.