If you have older hardware, you might have difficulties getting the drivers to work.
One issue of note is the loss of the XDDM video driver subsystem that allowed video drivers from XP to be used on Vista and W7. Microsoft removed it from W8 and later OSes. So if a WDDM video driver was never released for your graphics chipset, you will be stuck with VESA SVGA video under W8 and W10.
There are still a number of Pentium 4M and Pentium M laptops in use where this is an issue. I have an older Thinkpad that I use when on vacation and that the kids use at home that has the i855GME chipset. I have a friend that still uses her Inspiron 5100 that has an AMD Radeon 7500M chip. Neither will ever see a Microsoft OS newer than W7.