*nods to Kelly
Mayo, Paddy and others are right, check with your ISP before you do anything. If the contract allows you to run a web server, then it will work just fine. If they say you can't, dont, unless you're willing to run the risk of losing your account. If you are wanting to run I business site, then go to a real hosting provider for help. If all you want is to purchase your own domain name and use that for e-mail and a small personal web site, then go for it. Petra's link to a DNS provider is good, and there are others.
As for the time to maintain your own server...with just one, running an OS you are familiar with, all you need to do is spend the time necessary to stay on top of security issues and keep ALL unnecessary ports closed up tight. That time is determined by your present expertise. If you're not providing service to someone else for money, then it won't matter if it is unavailable occasionally.
Al should pipe up any time now. He's running a server.
See ya,