Plz HELP Why my vista is occupying 28 gb of space

I've installed vista starter on Windows xp. During installation query called selected Creating a folder called (Windows old). Off-late noticed 28 GB showing has occupied among 47GB drive. Eventually after deleting the folder "OLD" still no change in Free Space. I request you to suggest solution to retrieve 28GB Space. Please feel free for any further information required.
After the installation ive deleted the folder called Windows old from the c drive But still it is occupying 28 GB of space

Welcome

You said that you deleted windows.old, but it sure sounds like its still present. That space would have been reclaimed if it were deleted. Try doing it this way.

Go to Start > All Programs > Accessories > System Tools > Disk Cleanup.
In "Which files to clean up" dialog > Click on "Files from all users on this computer".
Select the Drive where your Windows.old is.

In Disk Cleanup dialog, select Previous Windows installation in the "Files to delete" list. Click on OK.