Extend XP built-in .zip support?

[d000hg]

The ability to view .zip files as folders is really cool. Is there any way to extend this functionality for other archived file types like .rar? Also. some file types like .jar are actually zip archives with a different extension. Is it possible to make XP recognise this?
Failing that, what's the best free tool for .rar on XP - a proper Windows tool not a command-line?

[FastGame]

Check out 7 Zip (http://www.7-zip.org/) and PowerArchiver (http://www.321download.com/LastFreeware/index.html#PowerArchive) both free.

[cash_site]

I use 7 Zip... damn, it is a very good compression app. it reduced a 10Gb app and files down to 700mb cd for one our projects! Very quick and has context menus with right click...

I also use WinRar, but more for its nice GUI app. ;)