Should I Get An ASUS P565 PDA or An Apple iPhone?

I'm in a midst of confusion here. I want to get a new PDA to replace my old O2 Zinc PDA and I have two choices. It's either an ASUS P565 or an Apple iPhone. The iPhone was my initial choice but I feel that it lacks certain function that the ASUS has. Can that be true? Also, I already have an iPod Touch so I feel that I already own half of its applications. Please help me decide!