Installing in User mode, or change once AD synchronised

I'm trialing SEP as a potential replacement for our current system, and have a quick query regarding the change from Computer to User mode.

Once I've imported an OU from AD, I am unable to change the endpoints to User mode; is there a way around this, or is there a way of installing the client so that it defaults to User mode?  For my current installation I could just delete the AD directories and change the client mode, but I'm considering how new clients will be handled down the line.

Cheers in advance!