I am sorry, the HW & SW Requirements webpage is not the clearest of support pages.
XP+SP3 and Vista were supported up through SketchUp 2014.
Windows 7 can run SketchUp 2015.
(Vista and XP SP3 support was dropped for SketchUp 2015.)
So you can run SketchUp Make 2014 on all of them if you wish.
SketchUp Make 2014 Download Links (provided here)
SketchUp Make 2015 - Maintenance Release 2
(and higher) supports skipping the 30-day trial period.
Edit first line of the .lic file to read:
##NoTrial
to suppress the 30 day Pro trial.
How to Skip Pro trial mode in SketchUp Make