In my opinion the Xbox is better. I think the gfx for their games out do the PS2 and they're slowly getting more titles out there, which rival the ps2 gameplay wise and ... when you tire of it, you can install linux on it
Over here we can hire our games out for a couple of days from our local video stores. In my experience with consoles this is a good thing as I tire quickly of repeatitive gameplay so it saves a fortune when I'll only play it a couple of times.
So therefore never backed up either an xbox or ps2 title but Tron is right, they both need to be modded. This is generally a relatively cheap process but tends to void any warranty.