Is this forever, or is it possibly just running ALOT of cronjobs at startup, and maybe failing some (which would make your system run slow)?
I prefer 'free' to show me info about my memory, it's a little more in depth.
~85MB to run some of the Desktop Environments, like KDE might be scrapin by. Switch to something ALOT lighter, XFCE, Fluxbox, Blackbox, twm
Or whatever, just something lighter.
That will help, and you should be seeing some improvement with just this.
If the disc is constantly "Cranking" then you might also wanna check out what's going on. Check your log files, usually located in /var/log or very close by.
/var/log/messages is your startup log file and that might also reveal something. I'd say you might wanna cut down on some services running.
Cut down running services you don't need, switch to a lighter wm (XFCE even claims to be Cholesterol Free
), and read your log files to see if something is REALLY slowing it down (due to long timeouts or whatever).