Sometimes adding opinions can make a simple project complex. Here is my experience, which you may find helpful:
1. Wanted an arcade cab for years, life finally led to a place where I have one, purchased by my WIFE at an auction for $30.
2. Generic woody cab in non-working condition with a somewhat common game conversion kit. Kit sideart slapped on the sides, marquee in good shape. 19" monitor was dead, game played blind. Rest of the cab in great shape.
3. Weighed options: Fix/replace tube monitor - out of my ability.
4. Decision: Replace tube monitor w/LCD, purchase RGB/CGA/YUV to VGA adapter and J-PAC. Leave original game and wiring and power supply in place in case I change my mind.
5. This allows many options: MAME, PS2 and Dreamcast games - plus the original game.
6. Emulation hardware - old Shuttle small form factor P4 pentium w/2GB of ram.
7. WinXP 32 as the OS with MAME, Mednafen, EPSXE (I don't like psxfin) and windows games.
8. MALA as frontend. * I have spent years using and trying out front ends. MALA has been the easiest to set up, best looking, works with vert/horiz monitor orientation. For a simple list frontend, I would use AdvanceMenu, for an eye candy frontend, I would use XBMC.
A few addendums: I agree with those who say that it's ok to convert a generic cab. I wouldn't convert a classic game cab. You don't need a super computer to run most mame games. You will be fine with a dual core intel. Core I5 is more than enough. I know there are a lot of hyperspin fans here, but it's simply too flashy for my taste. I was able to set up horiz and vert layouts in MALA quick and easy.
Expenses for were the cab ($30), video adapter ($40), lcd monitor ($35 - PA state surplus) and the JPAC with PS2 console adapter. ($70? - not 100% sure).
I am happy with the results and have zero regrets.