Free as in beer, I guess. :3
You're right though, i completely forgot about vmware server being free.

keep the existing setup and virtualize it (vmware is nice, but, xen is free)
upgrade the vm host hardware as needed or as necessary, instead of upgrading a machine that should really be left alone.

benefits:
1) minimal effort needed on your part
2) your dad doesn't need to learn new software as it is exactly the same, and all the data is retained
3) hardware upgrades are transparent to the client vm (hopefully)

(but, don't forget to routinely backup the data on the vm like any other machine though)

the first blurb was sorta believeable, then it went downhill from there..
(posting this just to get the achievement..)

Applied Cryptography