disable sql 2005 mixed mode password complexity?

I installed SQL Server 2005 for the first time today, and I set it to
mixed mode because that is how we have always had to configure 2000 in
the past for certain applications. I used a weak password for the sa
account, and it caught that, so I changed it.

The problem came when I attempted to install some applications that
previously worked under SQL Server 2000. The first one installed
without errors, but when I attempted to login, there was a connection
error and it said that the database login (which it creates during
install) was invalid. I set the connection properties to use the sa
login, and that worked (as this is a demo, I'm not particularly
concerned with security at the moment).

The next application I attempted to install actually errored out on me,
with some timeout error. When I tried to launch it after the failed
install, I again get connection errors. When I looked at the user
accounts in the Enterprise Manager-like addin (I forget what it's
called), I didn't see any of the accounts which should have been
created during the setup of either application.

Please let me know if I'm way off base here, but what seems to be
happening is that the applications I'm installing use weak passwords
for the SQL user accounts they configure, so they never get created.
Since the accounts are created by an installer, I have no control over
what password they use. So I just need to know if there's some way I
can disable the password complexity check for new accounts and get this
software installed. I'll lecture the developers on security later.