Re: Wireless Mice
I second the opinion on old Latitudes, I'm writing this on E7240 that is on its second screen. Replacement batteries are aplenty, just as well as they tend to have lot shorter lifespan than originals. Want to carry a spare anyway as run time is not always that brilliant. Nice 12.5" FHD screen (sadly the FHD version is glossy touch screen), fairly lite. Has built-in 3G etc so perfect for on the go.
Also at least so far Dell is nice enough to keep drivers and their own additional bits downloadable for probably all the way back (haven't looked past D620/625 as those are the oldest I have in use at the moment.