That's a lot of OS's for one little SSD. Why not put Windows 7 instead of XP by the way?
But what you basically have to do is not plug in the HDD when installing the OS's (just leave ONLY the SSD plugged in) and then install Windows XP (or Ahem, 7) and THEN Windows 8.1. Dual booting is easier if you install the older OS first in my experience. Then, when all is said and done, plug in ONLY the hard drive, open your BIOS at startup and make sure it's configured for IDE. Then plug in the SSD, boot Windows 8 or XP and plug in the hard drive when booted up. It should allow you to move files to it now.
Hope this helps! Also, don't quote me on this process, I've done lots of weird booting things (iMac with OSX, Windows and Linux as well as my Lenovo desktop with 7 and 8) but I can't guarantee that this will work perfectly.
If you need more details on setting the SSD as the boot drive, watch this https://www.youtube.com/watch?v=qMo8krAJd5Q