Ok, lets get serious now. I did have the identical system. Like the rest of the guys said, you can't overclock it. First of all, the bios is locked, just like Dell's system. What this meant is that you don't have the option to change the FSB or increase the Vcore. I also tried the hardware overclock. That mobo is the old type, and also requires you to move some jumpers to set the clock speed. I did that, and nothing changed.
Unless it's an alienware, you can't overclock any manufacturer's computers. That have to do this to protect themselves. PIII is sooooo outdated already and you can't play any of the games today (at least at a decent resolution). Even P 4 are almost outdated. Intel is going to release their next generation CPUs latest by the end of the 2nd quarter this year.
If you can't wait, wait a little longer until the next generation CPU's and standard is release. But this wait can be as long as 6 months. If you can't, go get a P4 2.4C or the AMD Barton 2500, with a very powerful video card. These will be your options for now, at least this is what I think.