use unrar, it's quick and simple - mandrake rpms are available from
http://plf.zarb.org
or just google for a tarball
then: unrar -x $filename
courtrrb is right, file-roller _can_ open .rar archives, but it's only a front-end to the command-line compression tools. If your distro doesn't have native .rar support, file-roller won't.
If command-line tarball support wasn't included in the distros by default, fileroller wouldn't be able to open them.
<mini-rant>
typing: $compression-tool -$options filename
is quicker than using file-roller. Tab-completion and <Ctrl> + <R> are your friends.
</mini-rant>
HTH