maybe mk1 but not 2 or 3. Search for the minimum specs; they are somewhere between 1.8GHz-2.4GHz Pentium IV class; maybe lower for Athlon XP/64 , Core Duo, and Core2
A keyboard hack for a one-player setup or only a few inputs is one thing, but for a 2 player 5-6 button layout you may run into technical difficulties like key blocking. In the latter case, pre-built specialty encoders are well worth the time and trouble saved.
btw, these onboard graphics chipsets are usually ok for custom arcade resolutions:
Xpress 200
Geforce 6100
You could probably drive your existing monitor with a Micro-ATX motherboard with either chipset.
Here is one for $50You could pair it with one of those Celerons from your OP