I know this is way past the time of this post, but thought I would add that I am testing homemade MC and MM phone preamps developed by users on Audio Karma. So for around $100 you can build some amazingly high end preamps if you know how to use a soldering iron and have some electronics background.
Getting to my point, I have been running tests using the same quality MM preamp and MC preamp. While the MM is louder and more forward sounding, so is the noise it picks up between the tracks and when there are imperfections on the record. The MC is much more refined and because of the physical properties, as markphd described, much of the noise is reduced and the sound reproduction is much more open and "airy" in laymen’s terms. I can hear instrument and vocal detail I could never hear with a MM and I have a very good Stanton MM. I also have one of the least expensive Denon DL-103R MC cartridges. When I have more money, I will try a higher end MC.
If you have a good phone preamp for a MC that allows you to plug into the standard line-in like ’CD’ or on older amps ’TAPE’, the rest of the equipment doesn’t have to be as high quality except the turntable and the speakers. But the receiver does need to be good enough quality to have very low noise and reproduce the range of sounds from bass to treble without much deviation. But you can buy a receiver that does this for under $500. A reasonable pair of bookshelf speakers that can reproduce the awesome sound difference be had on sale for around $500 +/- $100. I picked up a pair of Klipsh RB-81 IIs for $450 (on sale for close to 50%) and they are head and shoulders above many others in that price range. And a turntable able to use a MC has to have what is called a low compliance tonearm (the tone arm isn't too light weight) and doesn’t have a builtin phono preamp unless it can be turned off. These can be had between $250 up to $500 for those with a budget. Read reviews and ask many questions before buying a turntable for use with a MC cartridge.
For most of you that don’t want to build your own a MC phono preamp the Emotiva XPS-1 is a great option (I don’t work for them). It supports both MM and MC and costs $179 retail direct from the manufacturer or through Amazon. It is on sale now and then and I got mine for $129. I use mine to test homemade preamps against as a benchmark.
IMPORTANT: many electronics, phono cartridges, speakers, etc. take time to "burn in" and sound much better when they do. Some people say this is bunk, but I have witnessed it first hand many times using blind tests with my friends.
I hope this helps someone.