My last Mac was a 75 MHz PowerPC. I loved apple products, but a number of the software packages I needed in college were only available for PC.
I swapped through a number of PCs, preferring AMD or high end intel stuff, even for day to day use, as the other stuff really does show a weakness in its lifecycle longevity.
My brother started college this fall, and decided to go mac. He got the 12" powerbook with the 20" cinema display. THe monitors on either are beautiful, even theough the 12" is pretty small to look at for a long time.
I have seen the I-books in the apple store. Though good as a basic computer, the monitor even on the larger ones leaves something to be desired. At the same time though, the monitor on a lower-end PC laptop leaves something to be desired also.
In reality, if youre looking at a laptop screen, even the new big 17" ones, youre doing your eyes a dissservice, and IMO your vision will suffer. The nest thing to do for regular use, even if you have a laptop, is to get an external monitor.
My newest computer is actually a mac mini. I stepped from a dual xeon Dell precision workstation to the mini, because all I really need to do at home anymore is internet stuff; work provides the computing power I need for everything else... Im not in school anymore.
If I were you, Id go with a mac mini and spend more $$$ on a monitor. If you HAVE to have a laptop, try and splurge for a powerbook - maybe look for the refurbished ones to save a bit of $. I think youl bve happier to get the better screen if you have to look at a laptop consistently.
In general, the rule is to spend the $$$ on computers used constantly/regularly, and spend $$$ on hardware for computationally intensive work where not much time is spent looking at the screen. At the same time, realize that the less you spend on hardware, the lousier machine youll have with a more limited lifecycle longevity, but chances are your eyes are more important than a few bucks here or there on a CPU, or even the need to replace it after three years instead of four...
JMH