Here's any easy way to compress/decompress *.exe files with the popular UPX Packer
1) Place UPX.EXE in the c:\ folder
2) Go into your SendTo folder ...
Win9X >>> c:\windows\sendto\ (I think)
WinXP >>> c:\documents and settings\USERNAME\SendTo
3) Create a new shortcut in the SendTo folder
4) For the location of the item choose c:\UPX.exe
5) For the shortcut name something like UPX Compress will do.
7) Right-Click on your shortcut and choose Properties
In the target field enter C:\upx.exe -9 "%1"
Now, when you wish to compress/decompress an *.exe just right-click and select Sent To -> UPX Compress
NB: You might see an error message in the dos window but the compression still goes ahead.