I have the exact same powerbook. Now on ebay they're selling for about $1000. (especially if you have applecare still). You could sell it and buy a MacBook almost flat out. (might as well keep the portability) Don't you love Apple resale value?
Once I get a new job, I'm probably going to sell my powerbook and get a Mac Pro. $1000 off makes it only around $1500, which isn't that insane.