|I would not delete them. Compression is a way to save some space on files. Dunno why MS thinks old files are better ones to compress.|
One would have to know exactly what files are needed. Even experts might be fooled by some so I would only suggest you not delete any. It may be possible if you think they are no good files to put them in trash can in case you need them back.
See this link
and here maybe.
Windows 7 will not help if you have too small of a hard drive by the way.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.