Xp had to go mate. There are many reasons all over the internet but for a modern computer with uefi bios and sad xp was a dog in comparison to 8.1.
As previously mentioned you can get a classic start menu such as, startisback, start8 etc.
8.1 has many features like music streaming, free games via the store,not to mention the subsonic boot up times.
If you are getting a i5 or better and are adaptable to new operating systems, go for windows 8 with a shell.
If your getting a dual core pentium with 4gb ram or less and don't like change then get windows 7.
PS windows 7 was as good if not better than xp in my opinion.