Opinions on my CND sub-1K build?

Well, I am a major noob at building computers. I usually just buy pre-made ones, so here's my current build (in CND):

NCIX P55 Bundle Deal Core I5 750 2.66GHZ Quad Core CPU & MSI P55-CD53 P55 ATX DDR3 Motherboard
http://www.ncix.com/products/index.php?sku=43239&promoid=1219
299.99

Seagate Barracuda 7200.11 1500GB 1.5TB SATA2 7200RPM 32MB Cache NCQ 3.5IN Hard Drive OEM
http://www.ncix.com/products/index.php?sku=33167&promoid=1219
99.99

Samsung SH-S223C 22X DVD Writer SATA Black OEM
http://www.ncix.com/products/index.php?sku=46792&promoid=1219
23.99

Antec Sonata III Black ATX 16IN Mid Tower Quiet Case 3X5.25 2X3.5 4X3.5IN 500W 120MM Fan
http://www.ncix.com/products/index.php?sku=24294&promoid=1219
109.99

Powercolor Radeon HD 5770 850MHZ 512MB 4.8GHZ GDDR5 VGA DVI-I HDMI DIRECTX11 PCI-E Video Card
http://www.ncix.com/products/index.php?sku=48575&promoid=1219
139.99

G.SKILL F3-12800CL9D-4GBNQ PC3-12800 4GB 2X2GB DDR3-1600 CL9-9-9-24 240PIN Dual Channel Memory Kit
http://www.ncix.com/products/index.php?sku=30384&promoid=1219
PM'd for 105.85

Giftcard for free ship $10
Keyboard $12
extra 120mm fan 8.80
Assembly $41.09

$8861.68 Total w some PMing still to be done

Any good? I just want a good enough computer to do some light gaming (D3, SC2 when it comes out). Would 500W be sufficient? IDK if the mid-tower case is any good. Had some good ratings, but I am thinking about just getting the Antec 300 + PS.

Also how much would

Powercolor Radeon HD 5770 PCs 875MHZ 1GB 4.9GHZ GDDR5 2XDVI HDMI DP DIRECTX11 PCI-E Video Card (http://www.ncix.com/products/index.php?affiliateid=4352418&sku=48581&promoid=1219 for 144.99) or XFX Radeon HD 4870 750MHZ 1GB 3.6GHZ GDDR5 PCI-E 2XDVI HDCP Video Card(http://www.bestdirect.ca/products/219263/XFX/HD487AZWFC/ for 156.99) differ with my current vid card selected?

For ~1000CAD, you could get this:

AMD Phenom II X4 955 Processor, pricematched to 167.94
ASUS M4A77TD Motherboard, pricematched to 84.92
Samsung F3 1TB Hard Drive, pricematched to 87.52
G.Skill Ripjaws DDR3-1333 CL7 4GB Memory, pricematched to 111.95
NZXT Gamma Case
Samsung 22x DVD Drive, pricematched to 20.23
OCZ ModXStream 500w Power Supply, pricematched to 61.35
Visiontek HD 5850 Video Card, pricematched to 279.99
Coolermaster R4 Case Fan, pricematched to 5.50
NCIX $10 Gift Card
Logitech USB Keyboard
PC Assembly

Sub-total: 941.38, Grand total: 1002.62 with shipping, taxes and insurance assuming you live outside of BC.

Updated:

NCIX P55 Bundle Deal Core I5 750 2.66GHZ Quad Core CPU & MSI P55-CD53 P55 ATX DDR3 Motherboard
http://www.ncix.com/products/index.php?sku=43239&promoid=1219
299.99

Seagate Barracuda 7200.11 1500GB 1.5TB SATA2 7200RPM 32MB Cache NCQ 3.5IN Hard Drive OEM
http://www.ncix.com/products/index.php?sku=33167&promoid=1219
99.99

Samsung SH-S223C 22X DVD Writer SATA Black OEM
http://www.ncix.com/products/index.php?sku=46792&promoid=1219
23.99
PM'd for 20.23

Powercolor Radeon HD 5770 PCs 875MHZ 1GB 4.9GHZ GDDR5 2XDVI HDMI DP DIRECTX11 PCI-E Video Card
http://www.ncix.com/products/index.php?sku=48581&promoid=1219
159.99
PM'd for 153.49 + $15MIR

G.SKILL F3-12800CL9D-4GBNQ PC3-12800 4GB 2X2GB DDR3-1600 CL9-9-9-24 240PIN Dual Channel Memory Kit
http://www.ncix.com/products/index.php?sku=30384&promoid=1219
119.99
PM'd for 105.85

Antec 300 Case
http://www.ncix.com/products/index.php?sku=29812&promoid=1219
53.99

Giftcard for free ship $10
Keyboard $12
extra 120mm fan 8.80
Assembly $41.09

$796.62 Total +15 MIR (821.02 before PM) not including PSU


I'd either get this:
OCZ 500W http://www.ncix.com/products/index.php?sku=33040&promoid=1219 pm'd to 61.35 with an additional $20 MIR. Grand total 41.35

Or

Antec 650W http://www.ncix.com/products/?sku=30037&promoid=1219 pm'd to 77.95


Thanks for the help guys, got some nice pricematching going on. So I guess pretty much everyone suggests the Antec 300. Any further thoughts? My RAM should be compatible right? The MOBO specs has an asterisk beside 1600...