Most Helpful Guy
The correct way to phrase your question would have been "HOW MUCH does hair color matter." The answer is very little, but when a girl changes her hair color or puts colorful hues / stripes in it, it is a pretty effing hot bonus.
-Dark blue streaks in black hair
-Dark, dark purple (so cute)
-The occasional red or strawberry dye job
these are all hair colors / color changes I've seen and they're pretty awesome, but not mandatory.