Just a few suggestions. For your res, a 5850 is better suited.
Samsung's Spinpoint F3 500GB is the same price and performs marginally better.
Get a SATA ODD.
The Scout is a nice case -- it's only problem is that it can be cramped. If you plan on putting an aftermarket HSF on that 930 (which I suggest you do), you might want to consider a different case. And it's not that the Scout is too narrow because IIRC it's 8.6" wide, but the top fan is placed very close to the top edge of the mobo, so you might have trouble fitting in a large HSF without having to remove it. The Scout is also a bit short, so if you do consider a 5850 (and naturally, CF 5850s), you'll want to look at another case.
Lastly, this is probably just me being picky, but I like to recommend PSUs with a single 12V rail, usually Corsair and XFX PSUs. But I'm only being this picky because most of the parts you picked are exactly the parts I would pick if I were building a PC right now.
About the graphics card:
Check out the benchmarks. Since you have a similar system to what is used to compare current cards these results will be fairly accurate.
Note the difference in frame rates between the HD5770, HD5850 and HD5870.
It will depend a lot on what games you intend to play, but considering how much you have already spent I'd get a little more and get the HD5850.
*I assume you are getting Windows 7 x64 OEM. You MUST get a 64-bit version of Windows to support all the RAM. Windows 7 is by far the best and the OEM version can be found for just over $100.
**Get a program to make backups of your C-Drive (Windows and programs) to a secondary hard drive. Acronis True Image is the best. Put the backup in a folder. I use the second highest compression setting and 4.3GB file sizes. Backup AFTER you have Activated Windows. Make a second backup after all updates, drivers etc and then a THIRD backup later. Even do a fourth which you periodically replace (can be done automatically. I do automatic, incremental updates then wipe this backup and start again every six months which works perfectly.)