As a former MMF-5 owner, I wouldn't sink too much money into that table. Don't get me wrong, it's a decent setup. I did a direct comparison of my MMF-5 (stock) with my friend's Rega P-25, RB-900 tonearm, and Grado Platinum cartridge. While the Rega setup was better, it wasn't sufficiently better to justify the price. It wasn't until I listened to a Teres that I noticed the change I was looking for. Most people think a Rega is a significant upgrade. It is...but only in terms of dollars spent (IMHO).
I'm from the camp that believes, in order of importance:
1. Table
2. Arm
3. Cartridge
If you buy a new cart, you're still using the same table and arm. If you really *want* to throw money at the MMF-5, just upgrade the replacable stylus. That's really all I'd recommend. You'd probably get more bang-for-the-buck by buying a record cleaning machine. Until you can buy a Teres, I'd wait on any other "upgrades". Just make sure your alignment is true and enjoy.