The center I volunteer for has received 22 Window 7 Professional PCs and a printer, all are networked to a 24 port D-Link switch.
What software could I use to configure multiple PCs at the same time. For example install software, configure system settings and also restrict access to certain websites (it is a children center).
The software has to be open source as we do not have any funds to purchase any licenses.
Active Directory running on Windows Server would be your best bet. Failing that there are a mass of open source options for doing a lot of this stuff.
Microsoft offers discounts for registered non-profits, and if you can make friends with someone at Microsoft, you can probably get them to give you all sorts of good stuff.
Well you've basically got 2 problems there. Setting up the computers identically and restricting web access. My votes are for FOG to image all of the computers to a standard image and OpenDNS to control web filtering.
As for keeping the kids from changing the settings, that's a bit trickier. You best bet for free is to try and lockdown the image, removing things like My computer, search box, start menu, ctrl+alt+del access. Locking down a computer is non-trivial but the harder you make it the less likely things will be changed accidentally.
There is a microsoft free software Microsoft SteadyState that can be used to lock down the configuration of the PC, i haven't used it in a production enviroment but it seemed ok so far, let us know how it works out
