There is an edition of SQL Server Express 2005 that ships with Full-text and replication support built-in. This edition is available here:
This edition is different from the regular version that gets installed with VS.NET 2005/8. Also, it looks like you need to uninstall that version before you can install this one. The installation of SQL Native Client seems to run into issues if one tries to set up both editions on the same box at the same time.