What is the exact difference between the pro version and the home user version before i decided to upgrade and also is it running smootly under windows 2003 server with out stopping or freezing
Goos
The most important difference is that the Personal Edition may only be purchased and used by private individuals, and not for profit: http://www.mairlist.com/en/home/info.php
As a non-individual, e.g. company, association etc., you have to buy the Professional Edition anyway.
Then there’s a couple of additional features in it as well, in particular the networked mAirListDB (with PostgreSQL backend). Here’s a comparison chart: http://www.mairlist.com/en/pro/mairlist-features.php
Windows Server 2003 should work fine, although you will have to install Windows Media Player to get the required codecs.