First Desktop Build

So I'm getting close to building my first desktop and need to know if this is doable and worth it. I have a friend that I work with who has an older desktop he is willing to sell for $150. I was going to part it for the hardrive that has windows 7 64 bit on it and probably the DVD Rom drive. If I bought all new everything else and use the hard drive with windows 7 on it will everything work correctly when put together?

These are the other components I plan to buy:

-AMD FX-4100 Zambezi 3.6GHz (3.8GHz Turbo) Socket AM3+ 95W Quad-Core Desktop Processor

-ASUS M5A99X EVO AM3+ AMD 990X SATA 6Gb/s USB 3.0 ATX AMD Motherboard with UEFI BIOS

-HIS IceQ X H687QN1G2M Radeon HD 6870 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card

-Antec EarthWatts Series EA-750 Green 750W ATX12V v2.3 SLI Certified CrossFire Certified 80 PLUS BRONZE Certified Active PFC Continuous Power Supply

-G.SKILL Ripjaws X Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3