ide and sata hdd

hi! i'm a new member of this community.
i am just wondering if i could connect an ide interface hdd and a sata hdd at the same time, with both drives having different OS.
i have first setup our pc with the sata hdd. i have installed a win xp pro on that drive.(the ide hdd is not connected)
after the setup, i have disconnected the sata hdd and connected the ide hdd.then, i have installed another os on that drive, xp home. after configuring the ide drive,i have disconnected it and returned the sata hdd. at that time, i was thinking of using the ide hdd as a spare drive, whenever my sata drive fails. but now, i want them both connected to the motherboard for easier access. is it possible?
will there be no harmful effects to both drives?
are there any steps before i connect them both to the motherboard??

thanks!