Overclocking will almost certainly be out of the question from the very beginning. First off because it is an HP "off the shelf" type system, and secondly (and more importantly) because it is a laptop and heat is a crucial issue. Cooling is sparse on laptop systems so adding more heat to the mix is a bad beginning.
Memory optimizers are pretty moot if you're running WinXP as the OS, but there are some good Windows tweaking guides available that should be of help. We even have a couple of them right here at TweakTown.