Software raid is generally as fast as cheap hardware raid (virtually any card $100 or less). Reason being they rely on the cpu to do most of the work anyways.
Quick tip, don't spend a ton of money on a real hardware raid card if you're going raid0 or raid1 (the most common two types), as it is actually faster using the cpu than a dedicated controller on the card. I remember seeing a review somewhere, and the software-raid cards (they're hardware, but rely on the cpu, like a winmodem) outperformed the hardware based ones everytime.
I haven't done software-raid on windows, but I believe you have to convert the drive into a dynamic disk, then it can do software raid. Hopefully someone else can clarify this, as I really only have raid experience in linux.
