After installing XP sp 3 my computer seems EXTREMELY sluggish especially if an additional user is logged on (but switched to my account).

Pentium 4 @ 3.4 Ghz 1 Gbye 400 mhz ram
on-board video requires 64 Mbytes main memory

Looking at Task Manager I noticed that if I am running Task Manager and Outlook Express w/no other user logged in:
CPU usage < about 5%
Page Fault usage about 400 Mbytes
Commit Charge about 400 Mbytes
Cache memory about 480 Mbytes

With 1 other user running Task Manager but switched to my user:
CPU usage about 55%
Of this, McciTrayApp.exe for the switched out user takes about 35%
Page Fault usage about 580 Mbytes
Total memory for all processes is about 200 Mbytes
Commit Charge about 600 Mbytes
Cache memory about 510 Mbytes

I suspect disk thrashing but no obvious sounds of disk activity.

System Properties / Performance Options / Advanced / memory usage optimized for "system cache".

Display stuck at 480*640 resolution! Huh?
Thanks for your replies. I'm not sure if Yahoo Answers has a "reply" function, so I will reply here.

I did set memory usage back to "programs" because that's the only way it would work. But my sluggishness problem remains.

Does anyone know why this became a problem only after I installed Service Pack 3? And, does anyone know what I can do to resolve the problem outside buying extra ram?

Thanks.

I suspect disk thrashing but no obvious sounds of disk activity.
ur right

try tune up utilities..this program will solve cache problem..
it normal if other user logged in..you can simplify change the properties on outlook express..change to non-automatic logged in..

set it to programs not system cache, it might help