Here is the quote from their web site:

"Oracle Database 10g Express Edition (Oracle Database XE) is an entry-level, small-footprint database based on the Oracle Database 10g Release 2 code base that's free to develop, deploy, and distribute; fast to download; and simple to administer."

http://www.oracle.com/technology/products/database/xe/index.html

We are currently testing against Oracle 10g Release 2, so we are not expecting any additional development effort.  We will, however, need to create a new VMware instance and regression test against XE.

It is a good thing we are developing a regression testing tool, because we have a bunch of databases to support:

• SQL Server 2000
• SQL Server 2005
• Oracle Database 9i
• Oracle Database 10g
• Oracle Database XE
• IBM DB2 Express-C
• MySQL 5

We would add Ingres to the list, but they do not support User-Defined Functions.