If I understand what you are trying to do here, you have several steps to do.
First, you want to use fdisk to remove the existing Windows partitions
from each disk. This will delete all the data on them.
Then, use fdisk to create a new Linux partition on each.
Then use mkfs.ext3 to create a new ext3 filesystem on each disk.
That should do it. They should be mountable at this point.
I know that's easier said than done, but a little research should help.