Just installed MDK 10 and upgraded to kernel 2.6.5.

Running on an athlon 2200 xp so changed kernel cpu config to Athlon, not i586...

But before and now I must say as a recent migrant from WinXP the GUI seems heavy to touch, sluggish.

Konqueror windows take that little noticeable moment too long to appear, and my web browsers (Mozilla, Konqueror, Epiphany) all seem slow-ish to load local pages. Thoughts anyone?

As a newbie I can't find a "Task Manager" equivalent in KDE to show CPU load, kernel load etc... Any tips anyone?

Any general tips re: MDK 10? Can it be turned leaner and meaner?

Mozilla and Konqueror are both heavy - try Mozilla Firebird 0.8 instead. Increase you mouse tracking and acceleration speed.
I use "top" from the command line to track load, although KDE system guard (System -> Monitoring -> KDE System Guard) is probably what you are looking for. You could also try turning on/off KDE menu fades/animations and changing their speeds in the options.
You might also want to look at XPde - a Windows XP UI for Linux but I haven't tested it on Mandrake yet and may be v. difficult for a newbie to install correctly.
I have MDK10 on a K6-2 533mhz with 256 megs - its slow to boot but far faster than 98 when running (as Linux uses all the free memory as commonly used disk cache).

I have a very fast system and I posted problems like that for quite sometime... (2 min for my home dir to open) then I decided to try a different Window manager and it made all the difference in the world.

KDE works for some people but not for me. So before you blame mandy, try a different WM.

If you're using and nvidia card, the drivers actually help the WM because it uses a lot more acceleration than windows.

To show CPU load and things like that, I'll recommend gkrellm http://www.gkrellm.net/

I use kde system system guard as an equivalent to the windows task manager. In KDE I can quickly kill an app by going ctrl->alt->esc to bring up the skull. I'm not sure if that's a KDE specific thing though.