My 'new' computer (I assembled it Christmas 2013 from the semi-best stuff at that time) has no problem running original game cd's, but I know setup and compability can be tricky issues indeed.
Running Windows 7 Pro 64-bit with a WEI value of 7.6, if that makes sense to anyone. I have no problem running MMH7 or MMX smoothly.
I remember having some compability issues before that on Windows XP, but I think I must have solved them as I managed to play the games back then after some tweaking.
I'm very reluctant to move on to something newer than Win7 - so for now I'll ignore all other OS after that. Don't try to fix what's not broken! (knock on wood)
I've usually run with PSCA parties in MM6 and MM7; which as you point out is a good combination strengthwise and fits well with the artifact/relic selection in the game.
Currently I'm running a KSDC party as an alternation - it's nice to have a Druid who benefits from all seven stats for a change. On the other hand the Knight only benefits from five stats, but he's immune to SP drain and also to insanity in a certain way. xp Also he comes with 10 rare magic resistance points. Of course as I recently learned from this board, personality and intellect affects the chance of getting cursed and insane respectively, so the points are not all useless - though it is close. My Knight takes care of disarming, repairing and perceiving. My Sorcerer takes care of identifying and my Cleric takes care of selling/buying which have always been my preferences. My Druid concentrates on the use of magic.
No diplomacy for me - can't remember if I ever used it :/ Anyone?
Also iirc isn't there an almost infinite XP exploit in ver. 1.0 when claiming the award from the Fire Lord after clearing his halls. I never tried or thought of using that one.