[Ti] Buying the "faster" Mac model

[John]

So, there comes a time when one must upgrade their mac.

I have a dilemma. I'm trying to decide between 3 different macs -  
mini, iMac, and MacBook. I can easily afford the mini. The iMac I can  
somewhat afford. I can only afford the MacBook if I get a freelance  
job that I might get. The mini will not be powerful enough for me in  
the long run. I need something portable so the iMac might be a waste  
of $$$. However, I CANNOT keep carrying my work MDD home every other  
weekend because my PB is too slow.

Here's where it gets tricky: besides an upgraded burner on the mini,  
or the larger screen on the iMac, what exactly does the *slightly*  
"better" machine get you? For the MacBook if I configure the two the  
same (memory, HD), the difference is $200.00. The logical part of me  
tries to tell myself the faster numbers do not matter, but the geek  
in me says go for the faster one. I see 256MB of SDRAM...but won't  
128MB be enough? 1 gig of RAM, but then I'll probably put a gig from  
Crucial in.

There is one thing that will make my decision easier (besides trying  
the MacBook out at the Apple Store):




Based on features (RAM, Video memory, processor speed), in each model  
line, which is the better deal?

That is, several years ago I bought the 550, not the 667. Would I  
have an extra year of life had I bought the 667?



Thanks!

John