Totally agree with @thequacker, it will be hard to get decent results on this platform as you'd be facing way too many limitations, starting from a locked CPU + BIOS settings, and naturally the fact that by design it tends to overheat much more than desktop PCs. If you're into modding, you can still take the laptop apart and build a custom case around its internal components (or build an all-in-one computer like this), but imho it won't be worth the effort here.

There was this one trick which allowed you to substantially speed up your CPU (supposedly around 25% increase in performance) without having to drastically improve your cooling system (read CPU cooler upgrade/liquid cooling), you basically tricked your motherboard into thinking it should be e.g. at 667 MHz FSB instead of 533. Assuming that your system is compatible and that it can handle higher fsb speed, you'd still have to max out your cooling system's capability - e.g. by replacing the old cooling paste with a new high quality one, adding a heat spreader if not present, improving venting etc. - and eventually you could go on with stability tests and temperature monitoring. However, going up so much in core frequency would also mean the CPU will be drawing much more power, probably more than the power supply is designed for, so this part would also need monitoring and/or upgrade.

All in all, OCing an old low-end laptop's CPU is a no-go; that said, if you need a more reactive machine, there are ways to amp up overall system performance:

• Use high performance power plan on Windows
• Update RAM to max size/speed supported, check your laptop specs
• Update drivers
• If you consider updating to an SSD, keep in mind it will be bottlenecked by the SATA I interface (caps @ 150MB/s), however these drives have become very cheap and you'd still benefit from a cooler+more silent fresh new drive
• Defrag/wipe the drive clean and reinstall the OS
• It seems your laptop ships with the resource-hungry Windows Vista, if you need to stick with it for some reason, consider disabling unnecessary functions to make it run a bit faster

Finally, here are some nice repurpose ideas in case you decide to dismiss your old machine