Open Task Manager to the Processes tab.

Order the processes in decreasing order of CPU usage.

Park Task Manager in a corner of your monitor.

Next time you experience slow performance quickly glance at Task Manager
and see what process(es) take up most CPU time.

---
Leonard Grey
Errare humanum est

Task Manager does not record Virtual Memory usage it records allocations
of virtual memory to programmes. Actual usage will be less and should be
within the allocations made to the programme by Windows.
http://aumha.org/win5/a/xpvm.htm

Try Ctrl+Alt+Delete to select Task Manager and click the Performance
Tab. Under Commit Charge what is the Total, the Limit and the Peak? When
the Total exceeds your RAM then there is a presumption that the system
is using the pagefile, although there are some processes that will use
the pagefile and not RAM.

You can do a better check on pagefile usage using pagefilemon.

Use page file monitor to observe what is the peak usage. Start it to run
immediately after start-up and look at the log. Pagefilemon takes
snapshots. You need to run it at the beginning of the session at then
run it again at intervals throughout the sessions. The log is Pagefile
log.txt. If you right click on the file in Windows Explorer and select
Send to, Desktop (Create Shortcut). The same applies to
XP_PageFileMon.exe.

A small utility to monitor pagefile usage:
http://www.dougknox.com/xp/utils/xp_pagefilemon.htm

Note that programs using undo features, particularly those associated
with graphics and photo editing, require large amounts of memory  so if
you use this type of programme  check these first observing how the page
usage increases when they start and whether the usage decreases when you
close the programme.

--

Hope  this helps.

Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~