Yeah, I was just looking for a way to do it all on my BB, without my computer.
Edit: wait, figured out how to do it. You open an email with attachments, click the trackball and choose "Open with BeamBerry," then you have the option of viewing/saving the file. Then you can use the BeamBerry program to move it to the SD card. Nice!
BTW, thanks for the quick responses, and love the Calvin & Hobbes avatar!