PS3 was wacky, but the 360 wasn't that different from a PC at the time. There were some differences in rendering API, it had a few features not available on PC hardware. And the CPU cores were actually slower than an equivalent intel, but you had 6 of them, rare for the time. If your game was relatively portable and already used a API relatively close to D3D, it wasn't too hard to bring it up on the 360. I worked on a 360 game FWIW.