GNOME or KDE?

[John & Peg]

Nearly all my Linux use has been using bash on boxes used as servers or
for machine control.  I used X ages ago on solaris and rs6000 boxes.
Now I have a Celeron 433 box available with 512 RAM that I want to set
up as a Linux desktop to really and truly begin my walk down the yellow
brick road away from the M$ desktop.  My questions are: 1) does this 433
celeron have enough horsepower for GNOME or KDE?  and 2) which of the
two is better suited for a new Linux GUI user?   I have RH 7.2.

Also, 3) are there any good open source development environments
available (replacement for visual studio or codewrite)?  (yes, vi is an
option, but I've become addicted to the color-coded keywords)

Thanks.