I'm sorry if I've overlooked the answer, but I've fought this all weekend and searched this forum (and others) extensively.
I previously had XP Pro 32-bit on a 320GB drive, and a 500GB drive set up with an Acronis True Image Home secure zone for backups. A couple of weeks ago I bought a 1TB drive and Windows 7 Pro 64-bit OEM. I added the new drive to my PC, formatted it, and did a clean (custom) install of Windows 7. Everything went well, I could dual boot to XP or Windows 7, and I love Windows 7.
Saturday I decided I didn't need XP any more. I did a final backup, removed XP from the bootup menu, and removed the XP drive. I can't boot. My BIOS says it can't find a bootable drive. If I put the XP drive back in I can boot just fine into Windows 7. I've tried the repair tool on the Windows 7 CD. I tried an update install over my current installation.
My long term goal was to move my Windows 7 installation to the 500GB drive and use the 1TB drive for backups. I did a clean install to the 500GB drive without XP present, but Acronis won't let me restore my Windows 7 backup (other than just files) to any other drive. I have two drives available, but Windows 7 backup only presents the CD/DVD drive as a destination.
I've just about resigned myself to starting over with the clean install I have now on the 500GB drive, but it's a lot of work to get everything installed and configured again. Does anyone have any ideas?