If it's any help. I completed my cabinet the week before Christmas, with a P3 450mhz and it would play a lot of the simpler games, but 2 player games were almost impossible and with a lot of lag (sometime just locking up). Fighter games just didn't work (Marvel, Street Fighter, Mortal Combat, etc) and most of the 2 player shooter games (1941, Metal Slug, etc). I had bought a 128 mhz video card and almost 500mb ram, but it just wasn't enough horsepower.
After Christmas, I built a new PC (not in my plans, but we'll just call it a "late" Christmas present. 250g HDD, 3g CPU, 512mb ram. IT ROCKS!!!
My advice is to use your better PC or build a new one (I don't regret it!)
btw, my son and I play Metal Slug all the time. COOL!
