I stand by my original suggestion - XP and Win7 installs on separate drives to dual-boot
That's always a good opion if you have legacy apps, simply don't want the hassle of a full reinstallation, have reservations about whatever OS you're migrating to, or installing an incompatible OS (a Linux installation for example).

I don't see any of those issues here though, so don't really see why either of the protagonists in this thread would need to go that way.

In fact, for both of these specific cases, I would argue that the case is crystal clear for a full migration to a 64 bit OS to start getting the most out of the machines they've invested in.