I have a server with Red Had. I have two (2) hard drive arrays running on raid. the first set is a 73GB pair on a raid, the second is four (4) 300GB drives on a raid systems so it looks like one (1) 600GB Drive. I have the OS on the 73GB Drive and wanted to use the 600GB as a storage area available for file and network storage. My question is how do I set up a separate volume group and logical volume that is independent? Also How do I share that out to the windows domain to which this server is connected? I do not want to store any data from the network on the 73GB drive set as I want to keep that isolated for OS only.

You can do that as you install the OS or post install but it is much easier if you do it as you install.

I would recommend to make all drives part of the array and that way you'll have more than 1 terrabyte of space. Make the 73GB drives a /dev/md0 (raid1) and the (4) 300GB drives a /dev/md1 (raid5); then you'll have 973GB of space to play with.

After you set the raids then use LVM to partition your logical volumes using all 6 drives. If you use 10GB for all your system directories, which should be enough space, then you'll have over 950GB of space for your data; that's almost 1 terrabyte.