Drive Letter Assignments

I had to have the Master hard drive in my computer replaced. I was told to leave the Slave hard drive disconnected while I installed my XP OS on the Master drive, which I did. I then connected my Slave hard drive. Now the computer reads the Slave drive as “F” instead of “D” like it is supposed to.

How do I re-assign the Drive Letters so that the Slave drive is read as “D” instead of “F”?

I’m on a ‘loaner’ computer right now and the owner wants is back ASAP.

I am a novice so pleeeeeez:D try to keep it as simple as possible. Thank you for any help you might be able to give me on this.