Upgrading - Looking for input

[cschear]

I've got a system thats been limping along with 4 5,400rpm PATA drives, crap memory & motherboard, and I want to do this right. Here is what I am looking to have in the end:

Stuff I Own:
Video: GeForce 8600GTS 256MB
CPU: Intel Pentium D CPU 2.80GHz
OS: Vista Ultimate (Plan on going 64 Bit)
PS: Antec 500W SP-500

What I'm Looking To Buy:
$160 ($80 Each)
(2) Seagate Barracuda 250GB 7200 RPM 32MB Cache SATA 3.0Gb/s Hard Drives.
http://www.newegg.com/Product/Product.aspx?Item=N82E16822148309
I am thinking of running these in raid0 for the OS, Apps, & games.

$139.99
ASUS P5Q LGA 775 Intel P45 ATX Intel Motherboard.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131295
I'm not looking to SLI, so the single PCI-E is fine.

$103.99
OCZ Platinum 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227298

Does this look like a decent build? I know the processor is getting old, but I figure that can be my next upgrade. Also can anyone reccomend a decent CPU heatsink for ~ $30?

Thanks for the input

 

[cschear]

Found this cooler, looks promising:

$39.99
Sunbeam CR-CCTF 120mm "Core Contact Freezer" CPU Cooler
http://www.newegg.com/Product/Product.aspx?Item=N82E16835207004

 

[effel]

Artic Cooling Freezer 7 Pro is pretty good for the price.