How to connect to dial up connection without changing the setting.

I am working off of a laptop with 2 services available for connectivity;
dialup and highspeen wireless. The wireless is sporatic at best so I would
like to have the option of MS Office Outlook 2003 connecting to the dialup to
send/rec emailwith attachments. Is there a way to configure Outlook to
connect to the dialup if it doesnt have a solid signal from the wireless
provider? Or perhaps can I force it to use the dialup connection instead of
the wireless? I have an dialup ISP set up (AOL) though I would prefer one
with a larger cache for the attachements but will deal with whatever I can
get. Someone suggested Yahoo for $20 year has a large cache but will it help
in sending large attachments? Guess I have two questions here.

thanks / Paul