It would depend on what you use your computer for, but you should really
upgrade to at least 256MB of RAM.
No, it doesn't depend on what the OP uses their computer for - anyone
that has XP knows that in a default state, without anything else
running, it will consume between 90~110MB of RAM just booting up and
logging in. When you add AV and then start running IE or FF or Word you
exceed the base 128MB of RAM in very short order. So, as I said before,
if the machine has less than 256MB of RAM it's under powered.
If you are using it for more than just
basics, go for 512MB if your machine supports it.
Anyone running a machine with 96MB of RAM is obviously not doing much
with it, and they were concerned about cost, so suggesting that they
moved to 512MB, while a good idea for many, is a waste for them. 256MB
of RAM would be an ideal amount for this users.