Has this PC been sluggish for quite a while? Or is this something new?
If the latter, try to figure out what has changed recently.
Ordinarily, 1 GB of RAM is more than enough for most XP users. However,
some people require more, depending on the type of programs they run. If
Task Manager is showing that PF *usage* is 2.3 GB, then there's your
problem! That means you don't have enough RAM for your needs.
Follow my advice I gave earlier (I see Leonard suggested the same
thing). After you reboot, just let all the programs that are set to
automatically run at startup do their thing. Don't start any new
programs. Wait until all updates and scans are complete. Then open Task
Manager. Click the Performance tab. Then note the three values under
Commit Charge (K): in the lower left-hand corner: Total, Limit, and
Peak.
The Total figure represents the amount of memory you are using at that
very moment. The Peak figure represents the highest amount of memory you
used since last bootup.
If both these figures are below the value of Physical Memory (K) Total,
then you probably have plenty of RAM. However, I suspect the opposite is
true. If so, this means that you are over-relying on the pagefile.
Now start running a number of programs that are usually in use anyway --
Web browser, e-mail client, etc. WoW, of course. Now have a look at the
total, limit, and peak values. Anything significant?
For now, I'll assume you're malware-free. Your problem is most likely
due to the combination of programs running combined with not enough RAM
to handle the workload. One other idea is to run Process Explorer:
http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
Do you see anything using excessive CPU cycles?
Finally, occasionally a hard drive's transfer mode changes from DMA to
PIO. If so, you will need to change it back. See:
http://www.technize.com/2007/08/02/is-your-hard-disk-cddvd-drives-too-slow-while-copying/
and
http://users.bigpond.net.au/ninjaduck/itserviceduck/udma_fix/