I think part of the problem though is that its looking like he'll need two computers, and one will have the potential to cover the earlier era anyway so he might as well go for it.
I remember asking something similar on Vogons and that's pretty much what they told me.
Here's that topic:
http://www.vogons.org/viewtopic.php?f=25&t=41593
It might help him, but essentially what I remember is that you'll need an XP machine for games from 199-2007-ish and then everything past that will need a second machine.