Upgrading to an i5 2500k, GIGABYTE GA-Z68XP-UD3 mobo. I have 4gbs (2x2) ddr3 ram, 4 7200 drives, & a dvd-rw. Currently have a 500w ocz. Newegg says I need a 650 but eXtreme says I'm good with 500. Do I need to get a new one? Probably gonna overclock the i5 once I get a better cooler.
If you're gonna overclock you might want to go with the 650 just to be on the safe side.
I wouldn't recommend reusing your RAM right now just because RAM is so cheap you might as well get new RAM for your upgrade.