please advise new guy, help about midi on a mac Options

I'm a new working with midi and I'd like some help.
this is my gear:  iMac 350Mhz and 192MB ram. I also have cakewalk metro 5 and cubase, but I'm just starting to learn them.. and I have an old yamaha keyboard with midi capabilities.
So far I know the mac plays midi through quick time music instruments... I believe it sounds like crap compared to the audio board on my old pc. and since my keyboard is quite old, I'd like to know if there's another way I can listen to midi files with better quality.. thanks for your help

[Synthetic]

hmmm... well in my opinion midi is always going to sound like cheesey lounge music if you use any midi file with general instrumentation... it sounds best to me when you actually pull midi into a sequencer and then assign the tracks to play a real synth or virtual synth.

The only app I can think of that may have better results for midi sound may be Roland Sound Canvas which was made for midi files. For really nice sounding midi... try importing a midi file into Reason and assign the midi tracks to corresponding sounds and modules in it... you can get really nice sounding files that way.... I took a Van Halen midi into it and it was sweet.... sounded like Eddie was playing a wicked synth for his guitar licks. Also, some midi files are better than others too... depends on who programmed them and how time was spent doing it.