first off: hello from Alberta! i'm in calgary, so i can't be all that far away
regarding the memory usage, as someone previously mentioned if you run GNOME or other non-KDE apps in KDE, your system will load all of those libraries into memory as well, and that memory will not be shared with the KDE apps (or vice versa) since they are different libraries. this is a great way to run up your memory usage.
but measuring memory under Linux is not easy. the old (and accurate) saw is "top lies". because KDE apps share several large libraries, it can seem like they are using more memory than they are. for instance, right now i look at dcopserver which is a KDE background process running on my system right now. it says it's using 20Mb of RAM, which is a lot for a simple backgroudn proces! but that includes ALL the KDE libs as well, which are shared between all KDE apps. if i look to the number just to the right (in the RSS column) it shows dcopserver really only uses 1Mb of RAM . doing a `cat /proc/30083/status` shows quite clealry that the libraries account for 18Mb of the 20Mb of RAM it's reported as using, with the rest being mostly RSS and DATA (30083 is the PID of dcopserver on my box right now)
moreover, Red Hat 8.0 didn't do a great job of delivering a well put together KDE. i don't know how much that may or may not have to do with the memory usage you may or may not be seeing, but using 450 MB is way more than KDE really "needs". in fact, i run it on laptops w/64Mb of RAM and it only goes a few dozen MB into swap.