Yes, except you can have only one version of Outlook installed.
The older version should be installed first, if it isn't already installed.
In the installer, you'll be asked which existing programs to remove, and you can
check some or none of them.
When there are two versions of Word on the same partition, they fight over the
same set of registry entries, each one running the installer to "fix" the
entries after the other one has run. To stop this, there's a simple registry
change -- read
http://word2007bible.herbtyson.com/2007/04/15/word-2007-and-word-2003-coexisting/