In a display of how rapidly technology moves, my post about cabs has been made obsolete.
Bring forth 7-zip (.7z), and while at first appearance it may sound like a zip ripoff, it is infact worthy of being linked with the most popular compression in the world as it could be set to replace it.
Beating both .rar and .cab in compression while being just as fast, the code being opensource, means that its constantly being improved, works across all platforms, and is quickly rising in popularity.
To start using 7-zip, I recommend you get www.PowerArchiver.com version 9 which has .7z enabled on the right click options by default. For the purist theres the 7-zip only client at the official website www.7zip.org and for those who need to make installers there is Inno ( http://www.jrsoftware.org/isinfo.php ) which is used by Mozilla Firefox.
So uninstall winrar, forget cabs, because all you need is zip for speed, and 7-zip for small sizes 🙂