I've always just used straight tap water for my humidor, but then a friend told me I should use distilled water. Does it really matter?

You'll find a lot of differing opinions on this. Some say it depends on the humidor liner, some say it depends on the quality of the water.

Personally, I prefer not to take the chance. If I'm going to pay a good chunk of change for a good cigar, I figure the least I can do is go to the store and pickup a gallon of distilled water. One gallon will last you quite awhile.

I had been using tap water, but my gf picked me up some distilled so I'm gonna start using that.

Does that mean you're going to actually hand out some decent cigars at our next poker get together Joe? The last ones you handed out were pretty much like cardboard, haha!