SP2 has a lot of additions and changes to WinXP since SP1. Things like the
Security Center and the new Firewall usually won't put much more demand on a
computer, but with memory as low as 128, it will make a significant
performance reduction.
If you still insist on running your computer with Windows XP here are a few
tips on how to get it running faster:
1) Go to your control Panel > Performance & Maintainence > Adjust visual
effects. Set this to "best Perfomance" Yes windows won't look as nice, but
you will notice a significant in improvement.
2) Visit
www.tweakxp.com and look under the System Performance tweaks. I
must warn you, many of these tweaks involve editing the registry and should
only be attempted if you know exactly how to execute the tweak. Messing up
the registry can render your operating system useless.
3) It may be a good idea to upgrade your memory.128 is the absolute bare
minimum required to run Windows XP w/ SP2. memory isn't expensive.
Especially if you were to upgrade from 128 to 256. You are looking at around
$40 for another stick of 128 MB. Look around. you may find it cheaper.
Last but not least, you mentioned you had a Pentium II Celeron. A Pentium
and a Celeron are two different types of processors. Having a Celeron would
be worse than having a Pentium. If you are runninng a Celeron, you may want
to consider upgrading to at least a Pentium II or higher. The older celerons
are extremely unstable when pushed to their limits. And a Celeron with 128
MB of RAM may be stressing your processor.