Question about upgrade path

[Nosifer]

Hey gang,

I have a question about what I should do, as far as upgrading my current desktop system for the holiday game season.

My computer was put together back in late 2008, and the main components are:
ASUS P5Q Deluxe LGA 775 Intel P45
Intel Core 2 Duo E8600 Wolfdale 3.33GHz LGA 775
2x VisionTek Radeon HD 4850 in Crossfire
OCZ Reaper HPC 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500)
2x Western Digital Caviar Blue WD6400AAKS 640GB in Raid 0
CORSAIR HX Series CMPSU-620HX 620W power supply

I also have a 1.5 TB Western Digital hard drive and a 64GB OCZ SSD that could be integrated into a rebuild.

I'm mainly concerned with making sure I'm in good shape for Battlefield 3, The Old Republic Online, Elder Scrolls: Skyrim, and Diablo 3 while keeping it 'bang for buck'

If I'm not looking to spend more than $500 this round, what would be the smartest use of money? Should I keep the guts I have now and just focus on a better graphics card, or would I be better served doing all new mobo, ram, and processor? I don't do any video encoding or real super intensive processor tasks..but I do tinker around with sound design in Ableton occasionally.

Thanks in advance for any insight offered!

 

[Super Nade]

For $500, you could upgrade to a Sandybridge platform.

2500K = $215
Motherboard = $150 (not sure which is the best one. Go with at least 2 x SATA3 ports.)
DDR3 = $55 (8Gb)

 

[Knufire]

+1, a new platform is going to be a much better upgrade in the long term.