Here's a tip I thought I posted weeks ago, but I can't find it on the website, so I guess I didn't. :(

Do you want to change the default file folder Outlook 2003 uses for attachments? While you can't set a folder for attachments you send, you can set one for storing received attachments. You need to navigate to

HKEY_CURRENT USER\Software\Microsoft\Office\11.0\Outlook\Options

and add a string value called DefaultPath then enter the folder path.

The next time you use the File, Save attachment menu, Outlook's save explorer opens to that folder.

For specifics, see
http://office.microsoft.com/en-us/assistance/HA011265401033.aspx

If you use an older version of Outlook or to make it easier to access folders when sending attachments, your best bet is creating a folder on the places bar. See http://www.poremsky.com/places_bar.htm for instructions.