Well first off Welcome (or welcome back since you have another account).
Ok, a $3000 budget for upgrades nets you a lot of abilities in what you can do. If I was going to do it for myself with what you had, this is my idea:
This nets you a powerful 6 core cpu that you can OC to 5ghz with little issues since I paired it with the H100 that you selected as well. Mount the radiator to the top of your case and you're good to go. I selected the cheaper Asus P9X79 board since you'll just be running a two card xfire setup and it still has most of the bells and whistles of the $400 mobo's (minus the triple or quad sli/xfire support). You can upgrade to a better board since you got $100 leftover if you want, but this is a good "basic" 2011 board. Plus the pcie 3.0 slots are 3 slots apart instead of two so you could just get away with running on stock air coolers and not run into cooling issues if they were stacked on top of each other like other boards.
I dropped in a pretty nice 16gb 1866 g.skill quad set of ram that run at 1.5v and cas 9 speeds for not too much money, but you could save a few bucks and just go with 1600 speed and be just as fast for gaming. You really only see 1-3% improvement in select programs when running faster spec ram and generally, its better to buy for lower timings than faster speed.
I swapped out the 256gb ssd for in favor of two 120gb agility 3 drives; run them in raid 0 and you effectively will saturate your entire sata3 bandwidth and still net 240gb as your boot drives. It's also a cheaper route by a few bucks to do this then go with one large ssd. Put your other drives in as slaves for storage and you should have quite a bit of room; at least to last you till you need to upgrade to larger storage.
The gtx 580's are quite old now days (580 cores came out in Nov of 2010...) and while they are fast, they are not cost effective, even as "top of the line" cards. Specially now that AMD's 7970 3gb cards are out and perform 30%+ faster each for the same price, it makes since to swap them out. You also get the advantage of running a proper x16/x16 setup on the new pcie 3.0 lanes since you have the 3.0 trifect going on... 3.0 cpu, 3.0 pcie, and 3.0 gpu's. Not like you need that much bandwidth now, but its nice to know to complete the set and get that +10 to dexterity for your paladin... lol
Anyhow, I'd personally just stick your current gtx 285 and hold out till kepler comes out; see how well they perform. They are expected to come out in the next few months; unofficially April/May seems like the target date, if not sooner; but it could also be later in the summer. No real word yet from nvidia on their time frame, but the budget keplers are suppose to come out this month.
While Enermax has made a good name for itself in a very short time as being pretty damn good quality high end psu's, I'd opted for the OCZ 1250 zx series psu since its one hell of a value at $170. Mind you, these are basically rebranded PC Power and Cooling units since OCZ bought them out a few years ago and the new Z and ZX series have gotten great reviews; although when they first came out it didn't do so well because their MSRP was double that of what you can find them now. I would have no 2nd though of running one of them because well.. I am running them. Solid performers, cheap price, fully modular... can't praise them enough. Otherwise, if you got the cash, I'd look at Antec, Corsair, Silverstone and SeaSonic high end offerings before Enermax.
I also added the cost of win7 and the g500 to the mix.
This should keep you future proof for a good while; the only thing I'd add is a proper raid card, a few 2-3TB drives and run a raid 5 setup for storage. You could also think about a complete liquid cooling setup, but honestly, your current case is a bit cramped (even though its a full sized case) to house pumps and large radiators.
The alternative would be to build around a cheap i5 2500k system like your original thought, but I'd swap out the expensive Asus Maximum IV board for the cheaper Asrock Z68 extreme3 gen3 board for almost 1/3 the price. Here's the 2nd idea:
This is almost very similar to the 3930k setup above but on the cheaper i5 2500k. The Asrock (which is owned by Asus, same engineers) extreme3 gen 3 offers pcie 3.0 support as long as you have a 3.0 cpu (the only one right now are the lga 2011 cpu's and the upcoming ivy bridge), but this future proofs your setup a bit more than the more expensive Asus offering. Plus if you only plan on running a two SLI setup, this is going to be the most cost effect setup and still net you a 5Ghz cpu.
The biggest down side of all of this is still going to be your current case, again, even though its still pretty nice. You only have one inlet fan and three outlet exhaust fans and the front fan seems quite limited since the front brezel covers it up (reduces efficiency) and the fact that the hdds are mounted vertically (which again blocks and reduces efficiency).
Personally, I'd look at replacing the case with a more modern one is more water cooling friendly so you can add in a huge 3x or 4x 120mm fan radiator on top and possibly a 2nd 2x or 3x 120mm fan on the front; then do a proper LC setup for your CPU and GPU's. With the 2nd setup, you do have $700 to play with, even when you spend almost 1200 on just gpu's.
A proper LC setup with an idea of cost is listed below
$130 per gpu block
$40-80 cpu block
$30+ misc hardware
So realistically, I'm talking about around $610 for a complete setup at the cheapest. Hardware can bloat to $100-200 if you use nice looking nickle plated compression fittings, but I went with the cheap idea of just barbs and hose clamps.
I wouldn't advise going with the Delta CF00 120mm fan because that thing is damn loud... 62dba is 10dba louder than a washing machine or dish washer. You will notice these things even if you had a headset on... Those things are built to be used in server racks as exhaust fans. Plus its 38mm thick, most 120mm fans are 25mm thick, which may not seem like much, but it could become an issue for clearance in some cases, specially if you stack them for a push/pull design on radiators.
And if you want proper cooling compound, go with IC diamonds; best on the market and quite expensive. Otherwise stick with cheap arrtic silver 5.