You should be able to create a query that will show the information,
The query will list the machines that have a device.name like XXX (XXX are the 3 characters that the machine name has - to determine the site)
Then you can adjust the columns to show the software you have installed on that device - note that this will then return a list of the software for each device, rather than filter the information to remove duplication - so it might be worth reviewing columns so you can see what devices have what on.
I have not tested this myself so I cannot be sure the level of results you will see if you remove the columns that are duplicating - machine name - from those shown.
Once you have a query that you are happy is showing you the information you need then you can either right click "View as report" or open the reporting tool and then you can create a new report - referencing the query that you have created, this can then be adjusted to show different information also.
I hope that this gets you going in the right direction to resolving this request.
Thanks Stephen, i can't believe i missed the choose colum button :-)
It's exatly what i needed