How to delete file from

I noticed two files, one *.exe and one *.idl were added to my

c:\windows\system32

directory after I surf for one website. I tried to deleted these two files but the files are read-only. I tried to set the folder "c:\windows\system32" to be not "read-only". Still cannot delete these files. Then recheck the property of the "c:\windows\system32" folder, it was still "read-only". I tried many times, seems cannot change it to be not "read-only".

Any advise ?????????????????
Thanks