Well, things are getting closer and closer to 100%. I've attached another terrible photo, before I got the plexi covering the monitor on, and I also see a couple of the player 2 buttons are popped out.
I'm certainly not building some of the gorgeous cabs you'll find on here; I just want to play some games.

Since my last update, I've actually gotten a better (free! well, in exchange for some work) computer. The controls are wired and installed, and I've got an older version (v.106) of MAME running.
You'll see I've got 6 buttons on the control panel (and things are fairly tight!) and then on the front I have two more buttons on each side, which I've set as coin and start.
The new machine is a 2.2 GHz Core 2 Duo, w/ 2.5 GB of RAM. I assume that's probably fast enough to the run the latest version of MAME, but then I'll need to get some new roms.
So far, my goals of a cab on a budget are succeeding-the only cash outlay I've had is the controls (~$60). Everything else I got for free or I have traded for. Which is awesome. (for example: the blue on the control panel is actually blue duck tape. It works!)
Current issues:
1) The controls I have are configured as game controllers through windows; but no matter what i do, what I have in the second player position MAME treats as player 1 when both are connected. Anything I'm missing there? Both show up as 'Generic USB Joystick' so I've tried to set the preferred in the Windows control panel, thinking maybe that was where it was set.
2) Selecting games via joystick in MAME doesn't seem to work. I have checked the checkbox for that. I am looking at setting up mala, but I haven't gotten any farther than reading some docs on that. Is there an option in MAME to exit the game back to the list with a button combo?
After these are all sorted, all I have left is to get the rest of the games I'm looking for, change the windows boot logo to a 'Winners dont use drugs' image, and get mame to auto-start on boot.