if it is the original xbox, do it. however if it is a 360... durr dont do it.
a PS2 is better for rpg's and nicer games such as devil may cry, while the load times on the regular xbox are longer and the game library is considerably smaller. This is because the xbox moved to the 2nd generation (360) when nintendo came out with its 3rd gen consul (Nintendo gamecube) and the games have stop being made for the xbox and are mostly made exclusively for the 360. however the PS3 came out late, and it was expensive so many of the good games are still made for the PS2 (for those who do not have a stead flow of income (under 18)). Therefore due to better games and a smaller system (1/4 size of xbox original) you should most definitely sell it and opt for a PS2.
Tech is better on the original Xbox then on the PS2. PS2 had better game support for that generation, though if you're going to be swayed by titles, it would be better to look at the exclusive releases for each console & which titles you can't get if you sell the xbox.
Xbox comes with a hard drive, which is the most commonly failing component of a computer, and it does impact your ability to save & play games, as the Xbox caches information to it. PS2 doesn't, so it's not going to suffer in the same way from age.
I wound up with both. Had an original Xbox and years later bought a PS2 on the cheap. If you're thinking about it, there must be a reason why. If you don't have the cash to have both, I'd say go for it.
I never had the original xbox, nor did I want to, imo, it was crap. Ps2 had such a large amount of great games, and all I ever knew xbox or was halo, and I hate that game.
If you never owned it, can you really put an accurate opinion out there on it? Halo is not a reason to buy the system. It was well made, but in the end I thought it was a mediocre shooter.