Is it possible to maintiain my own DNS settings (for example, through ZoneEdit.com) and still be hosted by a 3rd party hosting company? (ie. not set my domain to the hosting company's dns servers).

For example, let's say I want mydomain.com and www.mydomain.com to point to the hosting company so that my web site comes up, but I want desktop.mydomain.com to point to my computer at home.

Thanks.

Yes, that's possible. Just create the appropriate address and mail exchange records.

Yes, but if the hosting company needs to do some changes which changes the IP-address, like moving your account to another server then you will get into trouble. I mean if you are on a virtual account without dedicated IP these things can sure happen.

Maybe look the other way around - are there hosts allowing you to add custom records to the DNS?