Not sure of an answer to your reasoning but I looked at your thread because the title intrigued me. "Try before you buy" Yes, you can try XP out if you wish. Borrow a copy from a friend and install on your system, it will work for thirty days but then expire as you will not be able to activate it.
It's perfectly legal to do this, Microsoft used to allow a download of XP to test if your system met the requirements, not sure if this is still available but it was virtually the full XP operating system that would work for thirty days.
Anyone not certain if they want to upgrade without testing XP can borrow an XP disk, install, test for thirty days then make a decision from there.
You will need to install on a separate partition or drive otherwise you will lose your current O/S and need to format and re-install if you decide not to upgrade to XP after the trial period. j.