one thing you have to always consider is how much you have to spend.
Alot of people seem to want the biggest and badest out there at higher prices and they dont need it.
With that being said, the speed you are asking about will do some of those things (slowly), but it the wrong kind of setup. Now what I would do in your situation (and I have been in your situation) is save that money you were going to spend and add some more when you can to it. Start looking for deals on either Blue and White towers or earlier model G4's.
Blue and whites can be found for $100 on up and earlier G4's for about $200-300 on up.
What is nice about these towers, is that with places like
OWC you can get all sorts of upgrades such as processors, ram, video cards etc..etc to make that machine much faster. You can upgrade some laptops, but not as much and usually at a higher price.
Start surfing some classified sections and find yourself a good deal on a tower that can be upgraded. For what its worth, I just sold a B&W tower for a little over $100 on a different forum. Someone could upgrade a few things and make that a pretty decent machine!
This is all of course the opinion of one :-)
Good luck and hope you enjoy your switch.
Rob