I think it's worth getting. If you don't want to spend 600 bucks, you can go with the 500 buck one. It's a little easier on the wallet. The 500 buck PS3 is just about as good as the 60 gb. The only advantage the 60 gb has over the 20 gb is the wi-fi connection and the various memory slots that most people don't even use anyway. I know I generally use USB flash drives because most computers have it, so I know I can carry it around to transfer data. Wi-Fi, well, it's convenient, but you're also more prone to people attempting to steal your access.
The difference between the PS3 and PSP is like night and day. PSP is a handheld, so it's not exactly a state of the art technology machine, but it is the most advanced hand held available. The PS3 is a movie player (CD, DVD, and Blu-ray), an internet machine, a video game console, and a tool to potentially find a cure to many diseases (folding@home).
No way to play PS3 games on a PSP.
You don't need a HD TV to enjoy the PS3. You know how people say the PS3 and 360's graphics are about the same? Well, do you hear anyone complaining about the graphics on a regular TV? No.