The dude above that said if you're using onboard RAID and not a RAID card is full of it. I have done two RAID 0's both with Vista 64 recently. Each board was using an Nvidia Nforce4 Ultra chipset and i have to load drivers. So I would say it really depends on whether or not there is an included driver for the particular RAID controller you are using.
It is correct that you don't have to use a floppy drive anymore. You can load them anyway you like (cd/dvd,floppy,flash drive....). You can even install other drivers at the beginning such as chipset and audio/video drivers. Just make sure that if you have a board/bios that allows you to switch off the ACPI function in the BIOS that your turn it on or else you will get dismal performance and it isn't something that is easily changed back once the OS is installed.