As others have pointed out (and as it should be noted generally) the Knicks aren't just going to sign and trade players already off their cap for Rasheed. More importantly, if the Knicks renounce a player, they have no more right to him than we do.
I'll also say that we'd be fools to turn down McGrady at the minimum. We took on Marbury two years ago, and while he didn't work out, he certainly didn't hurt the team. With McGrady, there's far more upside to the situation and there's no downside. Being able to bring in a wing off the bench who can score, handle the ball, create for others, and has size to boot would be a dream. And if it didn't work out, we'd be no worse off than we are now.