I think I did this wrong the first time...
My DAW PC died, and I took the HD out of it to see if my replacement PC would let me access the projects on it...don't laugh, I took me a while to find the courage to install a sound card!
Anywho, like I said, I think I did it wrong the first time when I put it in my backup PC. I don't remember ecactly what I was asked...something about installing Windows?, I don't remember, anyways, when I clicked on yes, after being congratulated, my Desktop from the DAW PC was now on my new desktop, as if the DAW HD was dominating, and the other HD was secondary. I also had no sound from the speakers.
After a little research on the web and YouTube, I didn't know about the "jumper" on a HD, where you can select "Master", "Slave" etc...the DAW HD was on the original setting. When I removed the DAW HD, everything was back to normal.
I put it back in, and copied my music stuff from DAW HD to the new, then took out the DAW HD and was able to play and hear my music projects on the repalcement PC.

I'd like to try this on another PC, but I should put that jumper on "Slave" next time, right?
Also, that DAW HD was used on a PC with XP Home, and I'd like to see if I can install it in a PC that has XP Media Center on it. My Sonar doesn't work on with XP Media Center, but I was hoping that if I put in the HD with XP Home, that I will able to use my Sonar on that PC, because it has more of everything...ram, etc...