Windows 7: best way to accomplish reliable high capacity backup

I was thinking of going with a software RAID5 (6x 2TB WD Green) which would give me 10TB of storage. I have installed Windows Server 2008 R2 and plan to use its RAID5 feature to manage my storage. I went software over hardware because if I experience a hardware failure, my array would be gone (or at least very hard to recover; would need to buy same raid chipset).

Am i correct to assume that if my OS drive crashes for some reason and I reinstall, it would recognize my existing raid array? Is there a better way to do this? I just bought a cheap comp with the following specs:

ASRock 880-GM (6 SATA, 2PATA)
Athlon II X2 250 3Ghz
4GB OCZ RAM
80GB IDE HDD (OS)
IDE CRROM

I have space for 6 extra hard drives which I will use for my storage array. Is my solution optimal or is there better? Thanks.