For what you want to do, any current portable should be fine. Considering that you're wanting to move from a desktop almost a decade old, any of them should be a step up performance wise. Unless you're wanting to play some graphics intensive games, a macbook should work as well, especially if you span it to a decent monitor. If they ever get around to updating the mac mini with the front end bus, ram and video card of the current macbook, it would probably work for you.
Can you get a windows desktop with better specs than a MBP for less? Sure, absolutely. Almost any desktop will have slightly better features for a slightly lower price compared to a laptop. But you'll still be stuck with Windows, and be hating it even more if Snow Leopard OS 10.6 does half of what they say it will. If you want to save a buck or two, consider getting an iMac for $700 less than the MBP.
OTOH, even my hating friends have to admit that the new MB and MBP's have a sweet design. It will run smoothly, and have a warranty for a year. You can buy an extended warranty that will give you three years of 24/7 tech support with a person who speaks English as their native tounge. If something breaks down, you won't have to trouble shoot what component is failing and deal with the manufacturer of that part specifically.
Go to an applestore or a best buy. Walk around and kick the tires of all the various machines and see if any of them appeal to you. Talk to a sales rep. Look on amazon ratings along with these forums and see what actual users have to say about the machines.
Your hating friends won't want you to try one, since they darned well know that once you start learning how to use a mac and os x, you'll eventually will quit buying windows software and use boot camp or vmware less and less. You think windows is a pain now? It'll be unbearable after using mac.
Good hunting, and good luck.
