Yes folks, well I got it up and running today and I'm surprised how well it did but in retrospect it shouldn't bee too surprising. It may need a couple upgrades but for $15 it's a pretty nice system.
$15 you say? Why yes. I bought a used 430W PSU to run it today. Otherwise it was just collecting dust. Here are the specs on this old Gateway I found a while back...
Pentium 4 1.3GHz (LOL!)
256MB RAM, it's mixed Samsung and something else...
GeForce2 MX (LOL AGAIN!)
8GB Seagate hard drive from like 10 years ago, but it is nice
But it's pretty good. I tried it out running Windows ME (Ugh, yeah I know, I still have tweaking to do) and booted the most demanding game I have at the moment I think, which is Strikers 1945 III. It did pretty well until there was a lot of stuff being drawn on the screen, then it crapped out on me a little. But this is on an ME system with crap parts, so I think I could do better with a less intrusive OS. It ran my favorite game, 1941, just fine as far as I could tell.
Now to finish the project, I'm going to build a replica arcade cabinet, mount the PC parts securely inside, and probably get an old TV and adapt it to RGB or something since large CRTs are very heavy and even expensive nowadays. Then run it through a MAME frontend, get some sticks buttons and coin slots, and we're in business.