That's a good setup, but I would get the latest AMD 8 series chipset over the aging 7 series since it has USB 3.0 and SATA 6 in the chipset. If you're not planning on using Crossfire, the
MSI 870A-G54 AM3 AMD 870 would be a good choice. The Asus AMD board you chose isn't high-end but more mid-range. Aside from the older chipset, AMD numbers them so consumers know what to expect. So AMD 870 or 770 are considered base chipsets, subsequent chipsets add onto these. The 880G, 790X, 890GX are mid-range choices with a few extra bells and whistles, the 790FX and the 890FX are the high-end chipsets which are considered flagship products. Also, the only way to get a guaranteed quad core is to actually buy one, AMD locks defective cores so system stability may be compromised if you unlock them. AMD will be showing off their new CPU's at CeBIT in early March, you may want to consider holding off until then if you are able. With video editing, the more memory you have the better, this is especially true if those editing programs are designed to be native 64-bit. Remember, you will need to reinstall Windows and possibly repurchase it if you are not using a full, boxed, retail edition of Windows. The license defines a PC by the motherboard, so, new motherboard equals a new PC. OEM versions of Windows are restricted to one PC, ever, while the other editions can be moved. This is a legal restriction, not a technical one, you can reinstall OEM editions normally and phone activate.