I'm going to buy the parts for my first PC build tomorrow and I was wondering if I should buy a floppy drive. I will be doing RAID 1 with 2 500 GB HDDs. The motherboard I'll be using is the Gigabyte GA-P55M-UD2 with an Intel i5 750.
You should be able to put the raid drivers on a usb thumb drive. When the windows disk asks for other drivers when choosing the disks to install on you select browse and select the driver on the thumb drive.
If you're going to install Windows so that it boots from the RAID array, then you will have to install early in the process the RAID drivers from an external source. Up to Win XP, the only external device the Install routines could access was a floppy drive. But in both Vista and Win 7, they also can use a USB flash drive as the medium containing the drivers - that is hinted at in the first paragraph of the manual page you showed. In either case (whether floppy or USB flash drive) you have to copy the driver files ahead of time to that medium (usually on a separate machine) using the optical disk that comes with your mobo.
So the answer depends on which Windows you plan to install. If you're going to use Win XP in any form, your will need a floppy drive and diskette. I do not know for sure whether an external USB floppy drive will do - hope someone else who does know for sure can comment. My suspicion is no - I doubt the Win XP Install disk has all the drivers necessary to use the USB bus system and use an external floppy drive.