If you have access to the original discs, you can use some of the recreated engines to get these running.
http://scummvm.org/compatibility.php
http://agisci.classicgaming.gamespy.com/sierragi.shtml (although ScummVM appears to do AGI now too)
http://agisci.classicgaming.gamespy.com/siersci1.shtml
Though, if you think Monkey Island has terrible graphics, you are going to hate a lot of these games.