Pro supports additional 'advanced' security for file and printer sharing, and it also supports dual CPU, IE AMD 4x4.
Apart from that Pro and Home are exactly the same. The Pro CD includes a handfull of files which are 'slightly' different from Home, when enable the additional features.
Home will support Intels Quad Core processor without any patches, as its license is per CPU, not per Core. They both use exactly the same memory, and thread management systems.
For a gaming system, unless you are going for 64bit edition, which is only available in 'Pro' then you might as well get XP home.
Unlike the crippled XP 'Basic', XP Home offers about 99.9% of XP pro's functionality.