Budget gaming build, need help choosing parts.

Approximate Purchase Date: I'm planning on buying the parts in the next week.

Budget Range: 600-900( Within that range)

System Usage: Gaming is going to be my main concern.

Parts Not Required: Keyboard and mouse.

Country: United States

Overclocking: Maybe

Monitor Resolution: Haven't chosen a monitor, but willing to take any suggestions.

I have chosen the parts that I think will work well. I'm just not sure between a few different ones and I could use some help choosing them. I would also love critique on any of it. Thanks!  

CPU:
Intel Core i5-2500K Processor

GPU:
Gigabyte GeForce GTX 560 Ti 1 GB GDDR5 PCI Express 2.0 DVI-I x 2 / Mini-HDMI SLI Ready Graphics Card, GV-N560OC-1GI
GIGABYTE GeForce GTX 560 Super Overclock 1GB GDDR5 PCI Express 2.0 2x DVI-I / mini-HDMI SLI Ready Graphics Card, GV-N56GSO-1GI.

Motherboard:
ASRock Z68 PRO3 GEN3 Intel Z68 ATX DDR3 1066 Intel - LGA 1155
ASUS P8Z68-V LX LGA 1155 Z68 SATA 6 Gb/s and USB 3.0 ATX Intel Z68 ATX DDR3 2200

PSU:
XFX PRO650W Core Edition 80+ Bronze ATX 650 Energy Star Certified Power Supply
Corsair CMPSU-750TX 750-Watt TX Series 80 Plus Certified Power Supply compatible with Intel Core i7 and Core i5

Case:
Cooler Master HAF 912 Mid Tower ATX Case (RC-912-KKN1)

RAM:
Corsair Vengeance 8 GB ( 2 x 4 GB ) DDR3 1600 MHz (PC3 12800) 240-Pin DDR3 Memory Kit for Intel Core i3, i5, i7 and AMD Platforms SDRAM CMZ8GX3M2A1600C9

Disc Drive:
Lite-On LightScribe 24X SATA DVD+/-RW Dual Layer Drive IHAS424-98 - Retail (Black)

Hardrive:
Western Digital Caviar Blue 500 GB SATA III 7200 RPM 16 MB Cache Bulk/OEM Desktop Hard Drive - WD5000AAKX

I was also considering getting this SSD , but it puts me over my budget. Are there any cheaper options for me to use that you would recommend?