ECC really does help. For home use non ECC memory is probably acceptable as most errors are going to be in graphics data etc. But, for a few $ more you can significantly increase your computers stability.

"Recent tests give widely varying error rates with over 7 orders of magnitude difference, ranging from 10−10−10−17 error/bit•h, roughly one bit error, per hour, per gigabyte of memory to one bit error, per century, per gigabyte of memory.[7][11][12]" http://en.wikipedia.org/wiki/Dynamic_random_access_memory