I am leasing shell space in a new building - need help with...

[Matt H.]

I am moving my existing business into a new strip center.  I have to do my own build out.  The building is currently shell space only.

Are there any free drawing/drafting programs out there you would recommend to help me design my space?  I am looking at 2000-2500sf for educational use.  Wide open space, I need one large classroom, a private office and 1-2 bathrooms (whatever local code requires).  Nothing fancy.  Basically a vanilla buildout with just a few walls. 

Thank you all.  Matt.