Help me choose solution between Apple Mac's possibilities (imac, macbook, macpro)

Hi guys

I do run on my Mac all day all year. I use it to work (design, web, photo) and for personal use to. It's a laptop so it is easy to combine both. I use it 85% work, 15% personal at home. I just pop into my head lately that I should get a second one just in case it dies one day....
I would also appreciate having 2 computers at home/office.

I presently run : PowerBook G4 1.5 ghz (2000$) + Dell 22" widescreen (350$) + 400gig exernal drive (250$)

I am looking to a solution to either

option 1 : Get a new mac (1800-3000$), keep the old one close.

option 2 : Get a PC (500$), keep the old one close, but will still need to be changed one day or another. (I like less the option #2 tough, but it is way cheaper)

...and as option 1, this is where i get confused... I can't decide if I would got for a macbook 13" - macbook15", or a imac 20" - imac 24" (and sell my widescreen), or go big with a huge macpro ??
I kind of appreciate the combo of having a laptop and close it to plug a big screen, it helps sometimes... but maybe the imac is the best bang for the buck ?
My Powerbook is bean running super great since the begining and it is gonna be 3 years soon so in one way I say why go for the huge macpro then. They we got the other ones to choose from, and why ?
Thanks for commenting !

I personally don't like switching back and forth from pc to mac because the mac usually logs in a lot faster, which makes me mad when I have to wait for ever for the pc to load something.

With the macs, it really depends on space, money, and what you really need to do on it. The Mac Pro would be my first option because you can throw anything you have at it. My second would be a Macbook Pro 15" for its performance and portability. If you are considering an iMac, I would suggest you look at the Mini's too. They are almost the same but cost a lot less which gives you room to upgrade to whatever monitor you want if you don't have one. I would consider the Mac Mini because it has the the power and graphics power to do great things. Not to mention the best one is 799!