You've got to wonder about a sanding tutorial that starts off with 2000 grit sandpaper.  It gives one a different appreciation for the word "smooth".  I don't know if I'll be buffing with 2 grades of polishing compound, but I'll probably try for a better finish than I was originally planning on.  Thanks for the link Javeryh.  You mentioned "a few mistakes".  Could you elaborate?
Sure.  First off, I couldn't find 2000 grit sandpaper so I had to "settle" for 1500 which I found at NAPA along with the rubbing compound and polish (it's an auto parts store).  The 1500 worked great - I can't imagine anything smoother.  I wish I could capture it with my digital camera but I just can't seem to get a good shot of it.  The finish is mirror-like but it's definitely not like a mirror... if that makes any sense.  You can see your reflection but it's not totally obvious unless you are looking for it.  Plus, I used a pink enamel-based paint for my base which my not be as reflective as the black enamel-based paint that the example I linked to showed.  Also, I will not be using this process on the inside of my cab around the monitor where I will be painting black - I don't want the monitor to be reflected anywhere and be a distraction while playing.
One thing I definitely learned is that 220 grit and even 600 grit aren't really smooth (believe it or not).  They are good enough for staining furniture that you will cover with a poly but if you want to apply a slick finish with no brush strokes or "orange peel" from spraying then a super high grit is the way to go.  It is a perfectly flat, perfectly even finish - like straight out of a plastics factory or something.  Definitely use a sander though - doing the whole thing by hand would be too hard, I think.
Now, there were three major mistakes I made the first time around that I think I've remedied this time (I have to sand and polish on Saturday so I'll let you know).  All are related to sanding.
1.  In my first test panel I can see very very tiny white spots in certain areas on the surface.  This is a result of the primer showing through after the sanding process because the initial surface I used wasn't 100% flat/smooth.  I'm using MDF.  MDF is really smooth, right?  I thought so but I guess not.  The first mistake I made was not sanding the MDF surface completely smooth before applying any primer.  On my second attempt I used a sanding block and 600 grit sandpaper to sand the entire surface of the MDF smooth.  The difference is very noticable to the touch.  Hopefully this will remove any "sand-through" spots.
2.  The next mistake I think I made was not sanding at all in between coats of primer and paint.  I think this makes a difference - even though I was using a high quality roller that appeared to be laying on an even coat I should have sanded each surfac smooth before recoating.  This time I used 600 grit sandpaper to knock down the current layer of paint.  I think this played a part in the white spots showing through because imagine putting on some primer but one dot dries higher than the rest - when you sand down when finishing it could show through because every other layer on top of that dot is on a higher plane.
3.  The third mistake I think I made was not sanding the edges of the MDF prior to applying any paint.  I noticed that when using the roller paint tended to collect along the edges of the MDF panel causing that area to be raised.  When I sanded it down during the finishing process I ended up completely removing the pink paint in some areas near the edge.  This time, I used 600 grit sandpaper and completely knocked off the corner edge of the panel - probably the equivilant of using a 1/32" chamfer bit or something.  This edge will be built back up by layers of paint and then hidden by the t-molding or whatever else is normally used to hidge the ends of panels.  Also, regarding the edges, I think I'm going to hand sand near the edges this time to be extra careful.  
Going through the process once really gave me a feel for what I was doing and I think I've pin-pointed where I went wrong.  With all that said, the panel still looks and feels amazing and I was very pleased with the results - I just want to make sure I get it perfect before trying it on my cab.  I hope this helps.    
