Time For New Computer Or Upgrade Some More??

So my computer is 2-3 years old. It was great when it was new but I feel that Im reaching its peak. I've upgraded as much as I can since I bought the system to try and keep up with new tech, but I don't think there is much more I can do.

So my current system is

-Intel Core 2 Duo E6600 2.4 GHZ
-4 GB PC5300 667mhz
-BFG Nvidia 9600GT 512MB DDR3 OC
-375 Watt Power Supply
-320 GB Western Digital + External 500 GB Seagate FreeAgent
-SoundBlaster X-Fi Extreme Audio
-DVD Burner
-Razer Lachesis, Razer Lycosa, w/ Goliathus mousepad and Armadillo cable management
-Samsung 26" inch T260
-Boston Acoustics 5.1 Surround Sound w/ 10" inch Sub
-Windows Vista 32-bit

I'd like to upgrade some more b/c I want a current computer, but is it worth it anymore? For example, I could switch to 800mhz RAM on my mobo, but it is very doubtful I'll notice any difference. Nvidia has their new processor, video cards are demanding 1000 watt power supplies, terabytes of internal disk space, holy $@#%! 

So, is it time for a complete overhaul of my PC if Im looking for the latest and greatest? Or is my current system upgradable enough to where I could still get alot more performance out of it with a few more tweaks and upgrades? I don't mind spending good money for an overhaul, but Im also not looking to spend thousands on a PC that will be middle-of-the-road in 1-2 years, especially if my current one can still last me a few more years with some key upgrades. Thanks.

you didnt say what mobo you have but supposing its from 3 yars ago its pretty oudated I say upgrade to this mobo

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=4132075&CatId=13

and this RAM http://www.newegg.com/Product/Product.aspx?Item=N82E16820161030

after you get this you coud upgrade your PSU since 300Watt is not going to cut it for todays standards as soon as you upgrade your PSU you could SLI that GPU with this one http://www.newegg.com/Product/Product.aspx?Item=N82E16814500018

and you are going to have a good enough upgrade.