Thank you for the advices. However I never even tried any HDD-OSD, so I prefer to stick on normal OPL, he wouldn't do any mess. I just thought to make things a little clearer having the pages renamed as I said (since on HDD page there will be the Ps2 games and on APPS page, a few Ps1/POPS games. Other pages will be disabled).
It is not much of a problem anyway, he'll quickly learn what pages correspond to.