As your sons' PC is new, I would guess that It's got a decent size HDD. Have you thought about creating a Partition for your Poser Runtimes? I did and it saves a lot of time doing Backups and Defrags.

Adriaan Barel (a.k.a. Vege Mite)
"Morality, like art, means drawing a line someplace." -- Oscar Wilde