(Hopefully) Finalized Budget Gaming Rig, Last Minute Check

Hi everyone. I posted a thread about a week ago asking about a ~$650 gaming rig advice, and I think I've got everything picked out after a lot more research, but (at least to me) you're the experts, and I'd like to run my finalized list one last time to check for compatability/catch a newb mistake.

Processor: AMD Athlon II X3 440 3.0 GHz AM3

Motherboard: ASUS M4A87TD EVO AM3 AMD 870 SATA 6Gb/s USB 3.0 ATX AMD Motherboard
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

HDD: Samsung 7200 RPM 500 GB 16 MB Cache Spinpoint
http://www.newegg.com/Product/Product.aspx?Item=N82E168...|SAMSUNG%20HD502HJ%20%25

Graphics Card: ATI HD Radeon EAH4870
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

PC Case: Either

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

or

http://www.newegg.com/Product/Product.aspx?Item=N82E168...


PSU: OCZ 550 W SLI ready Fatal1ty
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

RAM: G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-4GBRL
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

DVD/CD Drive: Sony Optiarc DVD/CD Burner SATA OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Monitor: Hanns-G 20" LCD HDMI 5 ms response
http://www.newegg.com/Product/Product.aspx?Item=N82E168...


If everything checks out, I'd like to order all this ASAP as my funding is secured. My aim is to have a decently budgeted gaming rig (games like Borderlands, Diablo 3, Starcraft 2, perhaps play games like Bad Company 2 without maxing out).

Is there any incompatibility here? Which of those cases would you recommend? Will the HDD/DVD Burner fit inside them? Does it matter if the PSU is bottom or top for this setup? Any friendly suggestions/warnings? This system will likely be only modestly overclocked at most.

Thank you very much. I appreciate your guys' insight and time.