You can delete those directories using Disk Cleanup.
Before you use Disk Cleanup, make sure that all of your files and settings are in Windows vista where you expect them to be. Deleting the Windows.old folder can’t be undone!!
Open Disk Cleanup by clicking the Start button, clicking All Programs, clicking Accessories, clicking System Tools, and then clicking Disk Cleanup.
In the Disk Cleanup Options dialog box, choose to clean up all of the files on the computer.
In the Disk Cleanup dialog box, click on the Disk Cleanup tab, click Clean up system files.
Select the Previous Windows installation(s) check box, and any other check boxes for the files you want to delete, and then click OK.
When you finish selecting the files you want to delete, click OK, and then click Delete files to confirm the operation.