Should I Upgrade?

You don't say if you have the 15" or the 17" iMac G4 800MHz. If you have the 17" you would be losing screen resolution. If you have the 15" you would have the same resolution, but just on a smaller screen.

If it worth upgrading? Well, the FSB is faster, the processor will be almost double the speed. And the harddisk should be the same size or larger. You would also get USB2.0 ports. Also, if you buy it after the next update, it would include Tiger and iLife'05.

It sounds like the update might be worth it, but you have to think about the differences in the machine and the cost to you to get the new machine over what you can sell the old one for.

As to where to sell, you could try the Marketplace and Classifieds forum here at MacRumors.

 

I would do it. The iBooks are really getting competative with the PowerBooks. I think you should go for it.

 

You'll love the extra portability of the laptop if you're anything like me. I'm on an 800MHz G4 iBook which I imagine at best has a similar performance to your iMac which for me is fine enough for now. Just the fact an iBook is a newer machine should mean it runs a little faster (computers slow down a little over time). But the speed differences may be reasonably hard to notice, the main part is the fact that a laptop leaves you the option to work wherever you want.

 

Can't you keep the iMac and get the iBook as well? Unless you're banking on the funds from selling the iMac to buy the iBook. A two Mac household is a nice thing to have.