Question about Ohms...

I have a KUSTOM GROOVE 1200HD which puts out:
1200 Watts @ 2 Ohms
800 Watts @ 4 Ohms
500 Watts @ 8 OhmsMy cabinet is a KUSTOM GROOVE G410H which can handle:
1000 Watts power handling
8 Ohms ImpedanceNow I have no idea what this means my question is:
Is this bad for my speaker/head and what does this information mean for me?

Solid state equipment can be ran at "non matching ohms", they will just not put out as much power, as shown on your amp. It will run most efficiently at 2 ohms.
With your amp 500 Watts @ 8 ohms into a 8 ohm cab that can handle 1000w, you should have no problems at all.
With tube amps, you have to match impedance, or else you can do damage to your amp over time, or fairly quickly.
Some say you can get away with it on tube amps, but I don't take the chance, nor would I advise anybody to do so.
Thats my understanding of it. You'll do fine, your amp just won't be running at its full potential. I wouldn't want to run 1200 watts into a 1000 watt cab anyway.

+1.
Since the amp shows the '@ 8 Ohm rating,' it will work just fine. Those numbers basically show you the amp's safe impedance operating limits and their corresponding power ratings. Since it's charted that way, running at any of those impedances is fine, as long as the speakers attached can handle the displayed wattage. (Which yours does.) If you had a second cab, you could run them in parallel for a total load of 4 Ohms, and you'd be getting 800 watts out of it.
Before you go thinking '800 watts?!?!?! Insane!' remember that wattage rating doesn't always equal actual volume representation. It's just a number that denotes power usage, basically. You might find that the 500 watts isn't enough to keep up with a 100 watt Marshall, for example. Power ratings can be a little deceptive, especially when it comes to clean SS power.
'What would be unsafe?' Running the amp in to a 16 Ohm cab. One could assume that a 16 Ohm cab would reduce the power down to 200250 watts. Which, in theory, it does. However, a 16 Ohm impedance puts double (or more, since impedance is more of a geometric progression) the resistance to the output vs. 8 Ohms. Since the amp isn't showing that rating,what would probably happen is the amp would be 'pushing' too hard to overcome the load, and burn something up. At the other end, a load that rates at under 2 Ohms wouldn't have enough resistance for the amp, which can also cause something to burn up.