Question: I added a new hard drive. When I check the system properties both the old and new drives are listed but the new one isn't assigned a drive letter.
Answer: If the drive is showing in system properties then Windows is recognising that the drive exists. The only reason that I can think of why Windows would not assign a drive letter to that drive is if the drive either does not contain a partition or the partitions that it does contain use file systems that are not recognised by Windows.
You can check what partitions are defined on your second drive using the Fdisk program. To run this select run from the start menu and then type in c:\windows\command\fdisk and click on OK. The program will first come up with a message about having a disk larger than 512Mb and asking if you want to enable large disk support. Answer Y and press Enter and the following screen will appear:
Microsoft Windows 98 Fixed Disk Setup Program (C)Copyright Microsoft Corp. 1983 - 1998 FDISK Options Current fixed disk drive: 1 Choose one of the following: 1. Create DOS partition or Logical DOS Drive 2. Set active partition 3. Delete partition or Logical DOS Drive 4. Display partition information 5. Change Current Fixed Disk Drive Enter choice:  Press Esc to exit FDISK
Assuming that option 5 appears then fdisk has recognised that your system has two disk drives. Select option 5 and select drive 2. You can now use option 4 to check what partitions are defined on that drive. Any partitions that are listed are not being recognised by Windows so you'll probably want to use option 3 to delete them.
Once you have a completely empty drive use option 1 to create a new partition. You will want to select option 1 on the next screen to create a primary DOS partition then answer Y to the question about using the maximum size and making the partition active.
You are now half way there. Once you reboot your system Windows will hopefully now recognise the second hard drive and assign it a drive letter. You will still be unable to actually use the drive until you format it. To do this right click on the drive in My Computer and select Format from the menu. Select to do a Full Format and then click on Start. Once the drive is formatted you can then start using it.
This article written by Stephen Chapman, Felgall Pty Ltd.