These are protected files, and there's usually a good reason for the system not letting you delete/rename them. However, if you feel you must, delete the copy in the Windows\System32\dllcache folder first, then the other copy. Additionally, if you're running XP with SP1, you may need to look in the sp1\files\i386 folder. This may be under the ServicePackFiles folder, but I can't verify that at this time.