If you run sfc /scannow and are prompted to insert your Windows XP CD, you need to make some changes to your registry.

First of all, you will need to slipstream your copy of WindowsXP with the latest service pack you have applied. For detailed unstructions on how to do this see: SlipStreaming Service Pack 2 into Windows XP

Once these files are on your hard drive, you can make a few registry changes to point to those location of the source files.

Start the registry editor by going to Start—>Run—>Regedit

Go to the follow locations and change the path of ‘Source Path’ to wherever you copied the source files on your hard drive.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\
ServicePackSourcePath
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\
SourcePath

Now whenever you want to run sfc /scannow it won’t prompt you for a cd.