IT support and Asset Management

We have around 120 computers and 30 printers with around 40 small and big upses. I would like to have a local webbased system whereby all the problems related to that asset is logged from when it was bought. with additional fields and also job card history. with customizable reports. if there is a open source software available. Also any user on the network would like to know about how to do things can go through the knowledgebase database and sort the matter out, and also log a request call to the internal support staff.

Additional features of having screen shots caputured.

If there is any software as such kindly let me know.