sorry im not familiar with the screen resolution specs for the dell....heres the apple resolutions.....
Display
Choice of built-in 12.1-inch or 14.1-inch
(diagonal) TFT XGA active-matrix display
Support for millions of colors at
1024-by-768-pixel resolution
Support for resolution scaling to
800-by-600-pixel and 640-by-480-pixel
resolution with millions of colors.
i would THINK (im not sure cause ive only played with a floor model ibook) that you would have to REALLY need to manage windows with a screen this size. i know that with my 15" tibook screen i find myself becoming obsessed with window management. here is a nice application that makes having lots of windows open at once, easy. think of it as the ultimate window manager.
its called virtual desktop and allows you to have different desktop spaces. i use one for the web and communications and have three other working spaces. its really just a glorified HIDE feature since switching desktops is actually just like hiding an application...BUT its much more intuitive and faster then using the HIDE feature in an application.
sooooo anyway...this is a link to version tracker were you can dowload and test it out.
CodeTek Virtual Desktop
OH YEA

I FORGOT TO TELL YOU. YOUR GONNA LOVE YOUR MAC
if you appreciate quality, then your gonna really like the mac user experience. so much is taken into consideration. im looking at the corners of the windows on my screen right now...they seem to have the same radius as the monitors frame on the casing

i would say this was a concious decision by apple...point being....they look at everything, EVERYTHING as a whole. its very integrated and harmonizing.