Upgrading for 2009: Thoughts/Advice on Using Old Mobo

EDIT: I've been told that OC'ing the E8400 to ~3.6GHz might be a problem on my older motherboard. Comments?

Was considering an all-new i7-920 build this month, but finally decided on simply upgrading the old workhorse as follows:

=== 2006 ===
CPU: Intel C2D E6600 2.4GHz LGA775 Conroe
Motherboard: ASUS P5B Deluxe P965 LGA775
PSU: Coolermaster 500W PSU
GPU: EVGA 7900GTO 512MB
RAM: Corsair XMS2 2GB DDR2-800 PC6400

=== 2009 ===
CPU: Intel C2D E8400 3.0GHz LGA775 Wolfdale
Motherboard: *Same motherboard*
PSU: Corsair 750TX 750W PSU (may want SLI in my next build)
GPU: EVGA GTX260 Core 216 55nm
RAM: Corsair XMS2 4GB DDR2-800 PC6400 (just adding 2GB of the same RAM)

I'm happy to stick with 2 cores since I mostly use the computer for gaming, internet, university research, and some average photoshop work for time to time. The benefits of 4 cores don't justify cost for me at this point

Basically, I am looking for any comments, criticism, or advice on pairing several newer parts with an aging, but so far solid mobo. Is it worth it to pay for a new LGA775 mobo to take advantage of faster DDR2-RAM or am I fine with PC6400? Is there anything else critical I should be considering before dropping money on a CPU and RAM that have almost no upgrade path ahead of them? All in all, I am just looking to enjoy some recent games at medium-high settings, hopefully including the Starcraft II beta this summer

Thanks for any and all input!

Thanks Calinkula

I was actually thinking of upgrading my display to the 1920x1200 Dell 2408WFP IPS with the money I saved from not going with Core i7, but I think the GTX260 will be fine