Which one should I get? i7 950 or 980x?
How much do you want to spend? 1k or less?
Also think to yourself, are the 6 cores really necessary? While I personally haven't jumped onto the quad-core bandwagon yet. I still don't think you'll have any use for 6 cores, even though it'll be cool as hell to have them. Very few games take advantage of multiple cores especially those above 6 so I think the i7 950 will probably be the best choice for you.
I'd look at a Xeon 5620 to be honest, 50% more cache and 32nm.
I guess I'll get i7 950 since it's going to get cheaper this August from $500 to $294 USD.