I use EPrints, which is great.

Do look out for Microsoft's offering though, which is in the pipeline.  It
will be free.  Of course It will need to run on a Windows server and will be
optimised for SQL Server.

David.


-- 
David Kane
Systems Librarian
Waterford Institute of Technology
http://library.wit.ie/
T: ++353.51302838
M: ++353.876693212