I have same motherboard, and I am using two 80Gb Seagate SATA drives in RAID 0. I get 80Mbps sustained, and 194Mbps burst(HD Tach). Because it is harder to recover from problems with this setup I would reccommend an imaging program to backup an image to external HD for peace of mind. RAID can only use equal amounts from each drive. While the motherboard can RAID PATA and SATA drives, I have no performance figures for this.
1) Yes, in your circumstance it is. Use HD backup/recover programs if your worried. Or Raid 5
2) Yes, but don't.
3) I think your particular board does support Sata2 raid 0. May be only certain ports though.
4) ATA133 = IDE. Don't raid a SATA and IDE drive together. My AthlonXP 1800+ system has a ATA133 Raid 0 setup. Get the picture?
5) It's software. A real Hardware Raid card is out of your budget, if you are saying an upgrade is out of your budget. Refer to mike99 about performance gains in regards to raid 0 on your computer (warning: performance may vary).
5) Is NVRaid a good controller? Or buying an external raid controller is a must? And is it a hw controller or a software?
Regarding 5), I am about to fit an XFX Revo card, http://www.scan.co.uk/Products/ProductInfo.asp?WebProdu...
This does not require drivers, as even the motherboard only sees the RAID array as an IDE drive. It does RAID 3 in hardware, so gives redundancy with 3 drives, or can be used with 2 drives for RAID 0 or 1.