Differences between MM or MC/Recommendations?

I really enjoy vinyl. I have two questions: What is the difference, sonically, between MM and MC cartridges? And, what recommendations can you make for a $1,000 and under retail priced cartridge?
My system: Rega Planar 25, RB600 arm, Rega Super Elys MM cartridge; Phonomena Phono Preamp (which is just about infinetately adjustable for MM and MC, also to be upgraded soon) Musical Fidelity NuVista M3 Integrated Amp; Sonus Faber Grand Piano (not the Home version); CAL Audio CL-20 DVD/CD player; Harmonic Tech interconnects; MIT T2 Biwire cables. I plan to keep everything except the cartridge and the Phonomema Preamp. Thanks in advance.
There are quite a number of very good cartridges now in either MM or MC configuration. Or even moving iron. I am sure that you could find a good selection in either category. Many purists will say that a top MC type will give more detail and quicker response. I tend to agree with this and have a MC myself. However MC have drawbacks too, like needing more step-up which adds either a transformer or more gain stages to the signal path. High output MC are very popular lately, as a compromise between both types. It is more important to get a cartridge that you like the sound of, and mates well with your system, than whether it is MC,MM,or MI. Just like it is with any other component, the execution of design, and the system compatiblity, may be more important than specs or theory. IMHO.
and with a rega table, i recommend dynavector cartridges. they seem to blend perfectly with the planar series for some reason. i used to run a 10x4 w/ a planar 3 and it sounded fantastic. i'd look at the 20x, which is available in high or low output versions.
There are good units in both types and Twl said things pretty good. If I could add through my experience over the years with both types, though no real generalization can be made due to the enormous offerings in both, I will say that I find most MM's I have used to be warmer in sound and the MC types to have more sparkle and clarity. I prefer most MC's I have used to the MM's but that is just me.
In your situation it would be more reasonable to spend only half of your budget for the cartridge and the other half to place either inside the pocket or upgrade the phono stage.
EAR 834P, Trichord Delphini, Trichord Dino and also Benz PP1 is on my list. The cartridge I would recommend is Benz Glider or Dynavector 20Xl.
I have a rega 25 and rb300 w/igconito rewired w/a clearaudio aurum beta s (a moving magnet) and it sounds great for jazz and classical.
I wish to echo, the response that Twl gave. "It is more important, that YOU LIKE, the sound, and that it mates well, with your system, than it's design". Beauty is in the eye of the beholder, and as you are the beholder, YOU get to say, what is beautiful. Trust your ears.
This guy Juki from HK has good deals on Ortfon MC's and other carts.His shipping might take some time but a freind got an SME arm and liked the price/service.Hey how do you like that Music Fidelity M3?What else was in the running when you got it?
Fletchi- Another thing that TWL said that makes alot of practical sense is "the execution of design and the system compatibility may be more important than specs or theory".
The numbers that a marketing department puts on a literature sheet doesn't make a sound!

To mention 2juki I've acquired from him Lyra Helikon for $1200 brand spanking new. I figured out that I really do not need Immedia's warranties on that since they're all don't make any sence becides I've got it at arround 45% discount.