Here's some results:
Test system: Pentium 75Mhz, 16mb RAM, 1mb onboard VGA, no sound.
Running ArcadeOS 2.50 from a 16mb compactflash card.
azurian : won't run, see error message in photo
blkhole : won't run, see error message in photo
cosmo : works great, 60fps (full speed) without tweeking
dingo : won't run (black screen, no errors)
futspy : won't run, see error message in photo
jumpshot : works great, 60fps (full speed) without tweeking
moonwar : works, 60fps (full speed) without tweeking but I need to configure mouse/spinner
rescue : graphics garbled, runs at 60fps though
schasrcv : works great, 60fps (full speed) without tweeking
spclaser : runs but has issues (seems to keep restarting every 3 seconds)
szaxxon : won't run, see error message in photo
The games that give the error below might be finding the computer a bit tight to work with, I'll have to try on a slightly faster or slower machine and see chat happens.
Nice progress though, keep it up!