Windows XP is before ssd came out and there just isn't any good support for it however win 8.1 will run on a normal hdd in mbr mode (at about 2/3 perform)... if your system has xp now then I would make an image of it first then install w8.1, open hyper-v or vmware and put the xp image onto a V-hardware.
if its a desktop system with xp on a normal hdd and the motherboard has ssd driver support then unplug the xp hdd,
plug only the ssd in and install W8.1 on it,
replug the xp hdd and set one of them as default boot in your bios
boot both systems to desktop 1 at a time and tell each system to NOT give any drive letter to the other systems harddrive... this is very important to keep them from mucking each others files and use [F12] or whatever the key is on your motherboard when you want to boot to the other option.
Since that you can just convert GPT to MBR disk after windows is well installed with third party software , such as AOMEI Partition Assistant. it won't cause you data loss, at least it didn't happen to me. after the conversion, make sure legacy boot mode is enabled.
The way you install an OS is dependent on how the Install Media is booted. If you want MBR, boot the media in the Legacy configuration. If you have an older system, this would happen normally. If you have a new system, you may have to turn off Secure Boot and allow Legacy boots.