Trying to get a historical timeline of Dell business laptops

For a software project we need to test on a wide selection of typical business-grade laptops (specifically with integrated graphics) which were common within the last X years. But I can't find this anywhere. For instance I don't know which Latitude models were for which year, and so on. This is making it very difficult to write a list of target test machines, or the range on hardware spec (CPU & graphics) we expect to encounter.

Can anyone help? Do Dell people read these forums - I tried to contact support but it demanded a service tag and I don't have any of those anywhere I can access them right now.

Similar information for other manufacturers is needed too, if there are any sites which record all this stuff? Wikipedia doesn't have a good completeness on dates unfortunately.

edit: I suppose another way to phrase this, if the data doesn't exist in the form I want, is:

"In each year 2005-2010, what are the typical low/mid-range business laptop/desktop models people would be buying" - this goes for HP, IMB/Lenovo, etc too if anyone has that information... maybe someone who works as an IT administrator might be able to pull up what your company was buying in each year?