$500 Budget Gaming Build - Advice/Comments

Approximate Purchase Date: This week, as soon as possible

Budget Range: $500 after shipping/tax

System Usage from Most to Least Important: Gaming, general multitasking

Parts Not Required: Keyboard, mouse, speakers, OS, Monitor
Preferred Website(s) for Parts: newegg.ca

Country of Origin: Canada

Parts Preferences: Doesn't matter as long as its atleast a GTX 550 Ti / Radeon 6770

Overclocking: Probably no.

Crossfire: Possibly in the future, but with a $500 budget, I doubt I'll be able to fit a crossfire/sli capable motherboard

Monitor Resolution: 1920 x 1080

Additional Comments: Will be used mainly for gaming (Starcraft 2, HoN, Diablo 3)

What I have in mind, roughly.

CPU
AMD Athlon 445 X3 @ 3.1ghz

Heatsink
Cooler Master Hyper TX3

Motherboard
Gigabyte M68MT Motherboard

RAM
G.Skill 4GB DDR3

Hard Drive
Western Digital Blue 500GB

GPU
GTX 550 Ti

PSU
Enermax 450w PSU

Case
Rosewill Destroyer Case

DVD Burner
LG DVD Burner

Total : $528.98 after shipping + tax

Any advice/comments are greatly appreciated. Thanks guys