A question on change of staus

I am currently H1b. My h1b visa is going to expire on
April 2004. I am going to leave my company on February 2004. Then I am going to go back to school on F1.
I have got admission and I am going to file for change of status just before leaving my company.
My question is: After I file for change of status,do I have to work, since I was previously on H1b visa? Are there any constraints on what I can do during my change of status? Thank you!