Windows – Install Winpcap on Windows XP without admin rights

Short: No.

Long: You can't because it requires rearranging the filesystem, which is dangerous because a virus defragger could rearrange the filesystem and then with a single block change, it could replace a vital program with its own version.

To install Cygwin on Windows 7 without administrator rights, you first have to rename the setup program of Cygwin (setup.exe) to something else (e.g. cygwin.exe).

If the Cygwin setup is named setup.exe, Windows 7 (or Cygwin?) seems to assume that it needs administrator rights to run.