In an miracle-like deal, I was able to get a 250GB Slim model in box for around US$35,00!
I am finally playing Ace Combat 6 (a game that I wanted to play for the last 10 years). I also got all the Gears of War games and some other stuff that are cheaper on the Xbox 360 than on the PS3.
I still have some doubts on how does the backwards compatibility with the original Xbox works, though. If I buy the disc of a game such as Panzer Dragoon Orta, will I be able to play it on the Xbox 360? Also, I've been a satisfied PSN Plus user for many years now, but is it worthwhile to pay for Xbox Live Gold to use it only with the Xbox 360?
Once again I appreciate all the replies!
Thanks for the help, guys!