Yes, I agree, Build your cabinet, Balloons are for P***ies.
I just got started on mine myself. Its tough to get started but once those parts come in it just seems to take off I think. Just follow the advice in these forums, most people in here know what there talking about and give good advice.
Being original is good to though so dont be afraid to throw your own ideas onto the cabinet. I went with the 3 inch translucent trackball myself. Put a flashlight or any small light under it glows in the dark and stuff, I was really happy with that.
Is this for mame i assume? What kind of specs you got on the pc? have you loaded it up yet. How does it run? What front end are you using? What kinda video card you using?
Also check out my project post on here, prolly just do a search on my id or soemthing.
Anxious to see the pics....good luck.