That software is fairly obsolete by now. You should download the latest "lockdown" version of Mach3 from
Newfangled Solutions » CNC Software Home of Mach3 . The demo version will still run 500 lines for free, so you can test out your system before throwing more money at it. You might like the newer screen-sets better too.
And no, a tablet isn't likely to work at all. Get an old (but not 10 years old) desktop computer running something from XP to Windows 7, 32-bit version, that has a parallel port capable of operating in EPP mode.