Difference between the 530 and 530J?

I've just purchased a Pentium 530 have no idea weather its a J or not, if fact i'm quite alien to this side of the computer world, i've owned AMD's since Athlon 1400's. I have got absolutly no idea what I have just got myself into, I've looked on newegg and there are two chips 3.0 E and a 530 J, both are for the 775 LGA and both are prescotts, thats all I know. What is the difference?

The processors with the J suffix are a new stepping, E0, they normally run a little cooler then the ones that don't have the J, they have the execute bit disable function, and i think they have better thermal controls but im not sure about that.

If you still have the box it will say if it is a 530J or not. If you dont you can download cpu-z and see what the stepping is. If its a E0 it is a 530J if its not then its a regular 530.