You can Overclock your Compaq, but it requires you to use a program called SoftFSB or CPUFSB, you have to identify the PLL Chips/Crystals (something like that) and see if they are supported by the programs. I haven't actually used this method myself, I just know that it can be done...others around this forum will know better about it...
Or basically you are thinking of getting a replacement motherboard for your setup?
It's possible that a replacement motherboard may not be compatable with your Presario case and Power Supply. You'd definitely have to find one used on EBay or someplace similar.
Even so, depending upon what you are doing with your system overclocking your 333mhz PII/Celeron processor may still not yield you the extra performance you may be hoping for. A 333mhz CPU is running on a multiplier of 5 x 66mhz FSB. If you are able to Overclock to 100mhz FSB you will wind up with 500mhz (5 x 100). A couple of years ago that may have been quite a performance gain, but for today's games and applications that probably will not provide enough oomph.
What are you trying to run on your system?
What kind of Memory and Video are you running as well?
In the end the best thing may be to save up for a new setup instead of buying old hardware for minimal gains. A decent AMD XP CPU, Mobo, Memory, GF4 Ti4200, Case, PS should be around $400-500us and will do circles around any OC you do on your current setup.
