Yeah, really depends on the software you are running.
I've stuck with Windows 7 on my PC stuff, although I do have an older laptop running Windows XP.
The recent Motorola and Kenwood stuff runs fine on Windows 7.
Some of the older software works better on XP.
And for the really old Motorola stuff, I've got a bootable USB drive running a program called "Rufus" that boots up into DOS.
If money is tight, it's pretty easy to find older laptops if you search around.