Are you trying to install your OS on a RAID array so that you need RAID drivers? Or, does your mobo use the same drivers for both RAID and AHCI? Then you may need to install the drivers. However, IF you are only interested in using AHCI, AND the OS you want to install is Vista or Win 7, those OS's have the AHCI drivers already and do NOT need them installed from a floppy disk. On the other hand, Win XP DOES need that floppy install process for any AHCI or RAID driver.
Some mobos' can treat a USB flash drive stick just like a floppy drive and let you fool Win XP into loading drivers from that source.
If none of that works, does your mobo have a floppy drive port? Even if you don't have a floppy drive and will not be mounting one in your system, you can borrow one or buy one cheap and connect it only temporarily to install those drivers. When done, disconnect the floppy drive and you'll never use it again.