While I do applaud the fact that you've kept the same system for 9 years, I can't help but wonder if it's due to the fact that you spent soo much money on it that you couldn't let it go. 9 years is waaay too long to hold on to a system...two Windows releases later! Every 6 months something new comes out, so imagine 9 years!
No matter what you do, you'll NEVER have the top-of-the-line system. Come to Taiwan and other such countries where they use Liquid Nitrogen to keep their processors cool and overclock the hell out of them...it's too much of a hassle to match them (while preventing yourself from freezing off important body parts...testicles anyone???). I understand what you meant by "top-of-the-line" = high end system that will last you for quite a while. But honestly, do you really need all that power? Unless you run some heavy task like transcoding and the conversion itself was time and life dependent, you don't need all this power.
The idea is to shop smart. I do agree with the above comments about the Core-i7 2600K, or even the Core-i5 2500K should be good (stick with the K versions...they can be overclocked better...for future reasons). I doubt you'll see much Real-World difference between the two, but it will save you quite a lot on the wallet. Or you can shop around for some decent CPU + motherboard combo deals and save big. I got a Phenom II 550 dual core. But it has two unlockable cores, thus making it a quad-core. Board + CPU only cost me $70 from Frys (they no longer have combos, but other stores might). I didn't get the best video card either. Rather than fork out a few hundred dollars on the top or near top card, I watched for sales and got a high end card for like $100-150 (GTS 250...u can score a GTX 460 for this price now). Everything else, just stuck with name brand items and looked for good prices.
Long paragraph short: If you just go out and buy the top-of-the-line stuff right now, it might cost you $2000 or more. If you play it safe and watch for prices, you can get a decent gaming system for $1000-1500. If you sit down and figure out the uses for your comp and get a system that suits your needs (compare price:performance as well), you can end up with a decent gaming system for $500-750 and then upgrade when you need to. I would say build a system that could last you at least 2 years, and then consider your upgrade options. This will save you a heap of money...you can use it to make a bed quilt and smell it every night as you go to bed

Examples(current prices):-
Core i7 2600K + Asus P67 = $480
Core i5 2500K + Asus P67 = $370
Phenom II 560(Quad unlock) + MSI 785G = $100
Radeon 6850 = $150
GTX 460 = $100