On a *nix system I can use a chroot to isolate 2 processes from each other and from the rest of the system. Is there any similar security system under windows? Or is there any way to prevent 2 processes from reading/writing to each others files?
I'm not sure you will gain anything on Windows by chrooting - do you have a specfic need?
In case any the top result on google is http://www.winquota.com/wj/.
Perhaps application virtualization might be an option? Microsoft has the following to say about it:
Not exactly like chroot. It does setup a sandbox for each program you specify. It can easily keep processes isolated.