George,
AFAIK, deleting the Mail and Entourage apps will not, unilaterally, provide the relief you seek. I think the files you need to delete are the associated settings and preference files. If you don’t do that, installing new apps is unlikely to resolve the issue. With luck, thems what really knows will add their 2 pence and confirm or refute my thoughts.
I don't use Mail or Entourage, so I can't add much re what files I think should be deleted.
That all said and to (finally) answer your question,
Pacifist will allow you to easily install the Mail app from the OSX install CD/DVD.
As for Entourage, the Office install CD supports Custom Installs, e.g., only installing Entourage.
HTH