If you live in a row house, you MUST insulate your crawl space. Before insulating the attic, from June-September, for each step I took upstairs, my skin was assaulted by a two degree difference in air temperature. Up, up, up the temperature went with each step (Since I am not Mr. Man, I never measured the difference, but I was usually crying at the second floor landing). Post-insulation, I don't notice a temperature difference UNTIL I get to the top of the stairs and it's like this, "Humh. Feels a little warmer up here." THAT KIND OF SANITY IS PRICELESS.
So now that some time has passed I'm going to recommend that you save up the extra $600-$1000 and PAY someone to install the insulation for you because it's money well-spent.