Statisticly speaking, only about 40 to 45% of users are using 64bit software, and useually are the ones running graphicly intensive software or games. Infact most software programmers use the 32bit versions.
It would if you are useing the 64bit ver of 7, otherwise you have to deal with whatever system cap you have. you have to be running windows 7 64bit to be able to utilize anything higher than 3 to for gb of ram.