Bizuser:
If you get the Seagate 1.5 TB drives, you may have to upgrade the firmware before using them. There was a batch with FW# SD15 through SD19 that would need to be upgraded. The FW# is on the drive label. Any with FW # SA21 and above are good to go. I had to upgrade the FW on mine and everything runs great.
You have to call Seagate phone support to get a special password/code to download the upgrade. They will then email you the code to be used for the download. They want to control the FW releases because there are different versions for different drives.
The upgrade needs to be done from a PC with SATA controller. It took me about 15 minutes to upgrade the 4 drives once I figured out what to do. The FW download creates a PC bootable CD. Once you have the drive connected to the SATA controller (I just disconnected the primary drive on my Son's PC), the CD automatically completes and confirms the upgrade. I then deleted the RAID5 config on the TS Live (losing any data). Next I replaced one drive at a time in the TS Live starting with drive 2 then 3,4, and 1, formatted it and went on to the next drive until all 4 were replaced. I then re-setup the RAID5 config and was good to go. I paid $119 for each drive on a special from Newegg.
Good luck