If your ISP are willing to provide suitable nameservers, then you can register a .com domain and point it at your existing webspace, which should give the results you want (http://www.example.com/whatever in the address bar instead of http://myname.ispname.example.com/whatever). Check with your ISP first, however, because they may not provide the necessary nameservers if you register a domain with someone else.
You can do something similar using frames (so called "masked web forwarding") if you have separate webspace with the domain, but it's not a very good solution.
"If youíre not using valid HTML, then you havenít created a Web page. You may have created something else, but it isnít a Web page." - Joe Clark