Building NAS and school use PC along with salvaged parts

Hello all,
I am planning to build a 24x7 AMD based Windows 7 64-bit home server that my daughter will also use for High-School work (no gaming) for next two years. And I am looking for a motherboard recommendations.

I can salvage the following parts from my old computer and other leftovers:
1. Gforces 84ooGS graphics card
2. 200GB IDE drive (Thinking of using it as an OS drive)
3. 400GB IDE drive (Will hold my loss-less music)
4. 1.5TB WD Green drive (Hold torrents, videos, and other computer backups)
5. Intel PCI Pro 1Gbps half height card (added it last year. Whole house is wired for 1Gbps)

New parts I am leaning towards as a start:
1. Antec Three Hundred Black Steel ATX Mid Tower Computer Case
2. ASUS M4A79XTD EVO AM3 AMD 790X ATX AMD Motherboard (Very highly rated. Does not have SATA 6)
3. SeaSonic SS-300ET Bronze 300W ATX12V V2.3 80 PLUS BRONZE Certified Active PFC Power Supply - OEM
4. AMD Athlon II X2 250 Regor 3.0GHz 2 x 1MB L2 Cache Socket AM3 65W Dual-Core
5. G.SKILL Ripjaws Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333 (8Gb would allow some Virtual Machines to run as well)

So, I was looking for a cheap and more importantly a stable board that does not require very many features like HDMI, etc. Just a basic stable board with workable audio (nothing fancy).

I looked at Asus M4A87TD and M4A79XTD (does not have SATA 6 though, highly rated). But the prices is 100+. Also, these Asus boards have Via audio that may not be stable for listening to music.

Can I go with "ASRock M3A770DE AM3 AMD 770 ATX AMD", a cheap boards since I am installing my own graphics card and my own nic?

I guess, is it worth saving $40 if I am going to loose 24x7 stability. What about power consumption difference in these boards?

Cheers. -aamitabh