stuck on the partitioning/grub install steps,

when im in the partition step it comes up with 3 listing of thing i can partition as follows

raid array device # 126etc -------which is the combind hard drives and which houses my windows 7 os etc

first hard drive sda i belive----- cant partition it with out erasing all the data

second hard drive sdb---- says pri/log free space but it wont let me partition it

trying to set up

pri--- boot

log-- /


and swap space

is there a way to do that with the raid array device? so i can install grub??

if not please explain how to remove the raid array so that my windows 7 os etc is in sda