WinXP VM will not start if I assign it more than 512KB of RAM

I P2V'd a Physical XM Pro machine that had 1GB of physical RAM installed.

I am using Fusion 8 on a mac mini (El Capitan) with 16GB of RAM to play the XP Pro VM but it will not start if I assign it any more than 512KB of RAM. The machine is very slow. It crawls. How do I fix this?