hokay, to convert a midi file into a wave file...

First of all, what's the point? You increase the size of the file by about a million times and it still sounds just as crap as a midi file played on a PC

Seriously, if you want your midi's to sound good you either need a hardware synth module or if your computer rocks really hard you can install an XG software synth. I use both methods, as it gives you much better sampled instrument sounds and proper effects modelling. None of this GM Wavetable bollocks for me!

Anyway, to the actual method...

The best way I have found so far is to use a software synthesiser called WinGroove. This will give you better instrument sounds than your standard midi sounds (in some cases, unless you've got a really amazingly expensive card), and some basic effects modelling too, like reverb and chorus.

By far the grooviest thing about WinGroove is it's ability to convert a midi file DIRECTLY to a wave file. It has variable sampling rates up to 44.1KHz 16bit Stereo (CD quality) and converts pretty fast. Download this program, play around with it, maybe it'll work for you. The results aren't amazing (next to my Korg Triton nothing is amazing!) but it certainly works, and considering it will cost you nothing it's most definately worth playing with.