Hi Rob,
I think I am in safe territory saying that XP is not supported.
It might work or might not. You would definitely need 64 bit XP.
Probably 2GB RAM.
If you can’t get Slicer to work, you might try ImageJ:
https://imagej.nih.gov/ij/
Another option might be Slicer 3.6:
https://www.slicer.org/slicer3-downloads/Release/win32/Slicer3-3.6.3-2011-03-04-win32.exe
Good luck!
Greg