It sounds like you are using TWC's Web based email. That is slow going. Try making a gmail account (hit gmail.com) and see if it's any better.

http://www.cnet.com/products/dell-latitude-d830/specs/ shows this laptop came with 1GB RAM which for today's browsers and sites will be not too fast. Sites are pretty heavy compared to the years this machine came out.

Vista didn't help much either. If you truly are doing it all web based maybe you can run a Linux on it. Web and Google Docs don't tax a machine much and it's not like we are going to learn Linux. Read http://tips.oncomputers.info/archives2004/0401/2004-Jan-11.htm