One company that has made such a switch is AIM Healthcare Services Inc., which audits erroneous health claim and payment forms to cut costs for insurers and hospitals. It uses a 9TB database running off a recently-installed SQL Server 2005.

Adam Solesby, director of strategic development for AIM, migrated the database -- the world's sixth largest, according to a September ranking by Winter Corp. -- from a Unix/Oracle setup to SQL Server running Windows server.

'Our needs are focused around... managing the sheer volume of data we have,' Solesby said. 'A key feature in SQL Server 2005 is its scalability options.'

Solesby also said SQL Server offered better features for a lower price than Oracle and will eventually support 12,000 concurrent users when its customers are given access.

Officials at Simon & Schuster Inc. said the publishing house used an automated migration tool to ease the switch from Oracle to SQL Server, which now supports 1,500 users.