acersnowman: since you can modify older games to work on newer systems are you also allowed to modify say HOMM 2 to work on moblie platforms such as android? I know that my phone has more horsepower tha the systems some of the older games were designed to run on.
Like zaine-h said, you can use DOSBox Turbo, which is the best solution, but bear in mind that getting good performance out of it is tricky on anything but the most expensive devices. I have a mid-range HTC One S and the best that it manages is Frontier: Elite 2. The DOS version of HOMM2 might be stretching it a bit.
ScummVM games like Beneath A Steel Sky, Lure of the Temptress, King's Quest, Police Quest etc. work brilliantly though, and I've heard good stuff about GemRB with Baldur's Gate.