64 bit home version limits you to 16 gig of ram. Pro limits you to 192 gig of ram. also microsoft support of home version ends in 2015 for pro it ends in 2020. Pro is only about 30 to 40 bucks more.
http://en.wikipedia.org/wiki/Windows_7_editions
There is a chart on this link that shows all the differences between versions. I have the professional 64 bit version and dont regret getting it over the home version at all.