employment agreements & open source

[http://dummy.us.eu.org/robert (Robert)]

Hi.  Dave said I should contact you.

My contract position may become a full-time permanent position.  I would
like to be able to work on open source/free software on my off-hours.
>From what I understand, this should generally not be a problem because of
Ca's lack-of-enforcement of noncompete agreements.  I guess the
only sticky wicket is the nondisclosure agreement.  Would the company I
will be working for be able to stop me from working on open source/free
software under the NDA?  The open source/free software that I may work on
will be orthogonal to the work I do at my company.

Thanks.