is a center channel really necessary??

I am currently redesigning the family room and have the option of installing a 5.1 system but have always been a 2 channel kinda guy. I love films and music equally, but assuming a fixed budget, may $4K, I know I could get a killer 2 channel setup but just a mediocre HT. MOst films I like aren't effects type, but I am concerned about hearing dialog clearly.

How much does the center channel matter?? Won't a set of good monitors image well enough to handle the dialog??