there is a seperate floppy driver on the intel website that creates the required driver disk, if you are still looking.
I always used to have a seperate partiion for the OS, just to keep things seperate, but there is no difference in speed, and as long as you back up your important data I can see no benefit of a seperate OS partition.
Raid 5 is significantly slower than the raid 0 partition that you are considering on anything but the fastest of hardware raid cards and give you little practical benefit unless you have a larger quantity of drives, if you require redundancy go for raid 10.
You intel controller will handle three drives in raid 0 no problems, it will do upto six from memory, or four in raid 5.