Can anyone advise which mail retrieval program is the best for the following scenario

I wish to download and store all my emails on a central server rather than on individual machines.

My current set up is a smoothwall dial up onto a network of 4 machines.
Linuxbox running samba
2 XP boxes and XP laptop on wireless.

From what I have read I believe that I need to use fetchmail to down load the emails but I am unsure how to configure it properly and what to do next. Am I right in thinking that I need configure postfix/sendmail to then read the location where fetchmail stores the mail and then set up the outlook clients to look for the mail server.

I have read a few things about this but this seems to be one of the more complex services to set up on linux. Which mail program would anyone advise to use - postfix , Qmail , sendmail etc.

Hope some one can help or point me in the direction of a good basic tutorial

I think your making things more complicated than they really are. Use IMAP and set it up to use IMAP on each machines client would be the easiest way to share the same inbox across multiple clients. You can use whatever MTA you want in this case.

Which MTA would you advise using