I recomend getting some or all of the following
Saftey glasses.
Some good files for clean up work after dremeling.
some small files with rounded faces for conture (SP) work
a roll of industrial sandpaper.
get the good cutting discs. not the heavy duty ones, the diamond inlay I beleive they call them. I could be wrong.
saftey glasses
I also recomend getting the pen attachment as it is smaller and there is somewhat less vibration going to your hand (Excessive vibration can cause nerve damage)
Sanding drums with lots of replacment sanding pads.
A dremel is a fun tool, But taking off large amounts of metal can be a pain. Window mods and such. I would also recomend getting a good jig saw and some fine metal cutting blades to do the major work, and use the dremel for the clean up. I today cut a window mod in a case that I have been saying I would mod for over a year. I cut a mask from "The Phantom of the Opera" using the jig saw to cut the big stuff, and the dremel to finish it. Looks great. Dremels are a god send.
Good luck, take it slow. and wear your saftey glasses.
Fix