[SwitchnSOON]

I am a switcher, so talk to me like I am an idiot.
I have a cable modem connection here at home, that I connect to over an Airport Network, and I have an earthlink account that I use as a dial up connection when on the road (which is often).
The dial up connection seems to be the default e mail, so how do I change the settings so that the cable modem account is default. (I am using apple mail-I can get mail from all the accounts just fine-just looking to set a default)
THANK YOU FOR ANY HELP.

[Altos]

There's a distinction to be made between connection types and mail accounts. It is not clear in your description wether you have a different mail account or not (earthlink) when using the cable modem connection.
If it is the same mail account, then you should go to network preference and either create a new location (which you will be able to select in the apple menu afterwards) or just reorder the port configuration (right of "show:") to make the airport port come before the dial-up one. This will prevent the system from trying to dial-up when you're at home because it will find the airport connection first.
If you indeed have two different e-mail accounts, then use preference to exclude them both from the "Automatic mail" (under the advanced tab). then, depending on where you are (at home or on the road), use "MailBox/Get Mail from Account" to get mail from the corresponding account.
When sending an e-mail, simply make sure that the appropriate mailbox is selected (in mailbox drawer under "In") before pressing the compose button or select the account on the message window before pressing "Send". Once you've made a selection for a particular connection type, it should remain in effect until you change connection type so you won't have to select the mailbox for the other mails you compose after the first one.