lighting headache

[Brighteyes_13]

my mind is running numbers and colors and i dont know what do do! argh!

ok here goes...

my husband and i are getting metal halides for my 50g, decided we like the idea of a 10000k bulb (may change this too) on a 250w ballast, but my husband is a DIY kinda guy and cant decide between a pulse(M138) or probe(M58) ballast.

What are the pros and cons of each?

also, what bulbs would you recommend for each?

I would really appreciate anyones response (even if its just to laugh at me)

thanks
Colleen & Brandon