MV = Mercury Vapor (if you look on JL's, it will be listed as "EYE" and are used only (as far as I know) for the Iwasaki 6500K bulbs.
HQI ballasts are typically used with double ended Metal Halide bulbs, but I believe the can be used with some mogul end bulbs (i.e. Radiums), but overdrives them giving them more output, but a shorter lifespan.
Pulse and Probe are another two different ways that Metal Halide ballasts can ignite metal halide bulbs, one requires a ballast and capacitor and the other requires a ballast, capacitor and a starter (I think that's what its called). Don't ask me which one is which though since I can't remember
Then there are electronic ballasts which can act as all of the above type ballasts (don't ask me how those work either).
Are you running actinics on this? If not you may want to consider higher kelvin bulbs. If you are, then 10000K should work well. I would skip the Coralife bulbs. The most popular brands of bulbs seem to be:
Ushio
Aqualine Bushke (aka AB) (love their 250W DE bulbs)
Hamilton (hear their 14000K is out of this world!)
CoralVue (currently running a 12000K 250W DE on my tank)
Giesmann/BLV (though I don't know if they make 175W bulbs)
XM
Radiums (Dez uses these on his bowfront)
I've heard mostly good things about all of the above bulbs, but they are usually more costly. The cheaper bulbs include Sun Aquatics, Venture and a few others. I've owned and run a Sun Aquatics 175W 10000K bulb and thought the color was nice (but dim). Quite a few other reefers have had problems with them being very yellow (almost 5500K yellow) though.
Also, remember that the color of the bulb may change a little after the initial "breaking in" or "burn in" time which is typically 100hrs or so. Oh, and remember to acclimatize your corals to the new light. You don't want them to go through light shock and bleach.