Hey, the PC is looking good. I would do couple changes though.
* WD 640 AALS (black) is only few bucks more expensive than 500gb. Those 320gb(320x2=640) platters perform a little better than 250gb platters.
Newegg.com - Western Digital Caviar Black WD6401AALS 640GB 7200 RPM 32MB Cache SATA 3.0Gb/s Hard Drive - Internal Hard Drives
* You can get 1066mhz RAM cheaper:
Newegg.com - WINTEC 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory - Desktop Memory
* VX550 isnt on pair quality-wise with another Corsair PSU's, because it's made by Channel Well Tech, instead of Seasonic. If by any chance, you can afford Enermax Pro82+ 525w,
Newegg.com - ENERMAX PRO82+ EPR525AWT 525W ATX12V Ver.2.3 SLI Ready CrossFire Ready 80 PLUS BRONZE Certified Active PFC Power Supply - Power Supplies ,i would recommend it. On top of excellent quality, it's also the most quiet active psu on market;
Modu82+ 625 Power Supply: Enermax to the Forefront | silentpcreview.com
* Also the S1283-EE edition you chose, it's a great cooler. BUT Xigmatek HDT-1283V has the same price.. Even though -EE has fourth heatpipes design , whereas -V(dark knight) has three heatpipes, the performance is the same according to all reviews/tests.
Why should you pick up the Dark knight edition then? The reason is simple, S1283V comes with optional LGA775 mounting bracket, it improves the contact between cpu and the cooler.
Newegg.com - XIGMATEK Dark Knight-S1283V 120mm Long Life Bearing CPU Cooler - CPU Fans & Heatsinks .I wouldnt trust pushpins.
* HD4870 and GTX260 performs almost the same. But the newer Core 216 version of the GTX260 is slightly better than HD4870. Even though your motherboard has crossfire support, i would still pick this:
Newegg.com - SPARKLE SXX260896D3S-HP GeForce GTX 260 896MB 448-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Desktop Graphics / Video Cards -sp216 edition, same price as your current hd4870.
* The UD3P mobo you chose has crossfire, do you really need it? Also if you go with the gtx260sp216 gfx, it would be kinda pointless.. You could pick up UD3R, which is the exact same mobo, but only has one PCIE X16 slot.
Newegg.com - GIGABYTE GA-EP45-UD3R LGA 775 Intel P45 ATX Intel Motherboard - Intel Motherboards
recommendation------------->
what about optical drive and case?