My computer was getting slower and slower to load programs and even go between tabs in Firefox. I did virus and spyware scans with nothing found then it stopped doing a virus scan altogether. Then it wouldn't reboot. The boot sequence stops at the two tone blue screen with the Windows logo. I think the windows installation has been corrupted. Can I reboot from my Windows CD and reinstall it? Will I lose my data? BTW this is a replacement drive for a smaller one that I still have. I tried reinstalling the original drive and making this the secondary drive but Windows Explorer doesn't show the problem drive when I boot the old drive. It boots OK.

Did you change the jumpers both the old and new drives? The old drive should be set to master, the new drive to slave as you said you did. Be sure to check the ide and power cables. Extract all the data that you can/need and be sure to burn them to a cd for a backup. If there is no data available, perhaps it was damaged by the virus and you will have to go to a shop that specializes in data recovery--not cheap!

I had the jumpers and cables set correctly. My plan was to put the drive in the slave position, boot from the old drive, recover the data then reformat that drive and put it back as the master and reinstall XP. Just don't know why it isn't recognized. Forgot to go to My Computer to see if it was there before I went to another plan. Probably wouldn't show there, though if it wasn't shown in Windows Explorer. Can a drive with Windows installed be put in a slave position for data only? If there are any other ideas I'd appreciate them.

Also, am I correct in thinking since Windows gets to the point of loading it does and then stops that one or more Windows files is corrupted or missing?

Yes is the answer for recovering the data. It could be a file problem or hardware. You would have to be able to check the error log to find out, or set the option to show errors during the startup to tell waht the problem is.