I don't think it would make games and apps quicker.
If you already have Pro then I would just install it.
There are a few differences in Home and Pro..i don't know all of them. For example: Pro supports dual CPU and dynamic drive.
Pro is also more customizable, like you can lock certain features and make certain tweaks that you can't do in Home without extensive registry editing.
I prefer pro for the networking options. Really useful for me if I am changing the networks all the time.
I have lost count the number of times that I have been at a LAN party and you get some one with XP Home ; and the computer refused to do any thing with the new network that we are trying to connect it too.
The other reason why i need PRO at home is that I need to connect to the office SBS server from time to time via VPM.
XP Home is many there for the standard end user that really does nothing more that keep is computer in the same envorment.