While a P4 won't work....
Some P2 boards will take certain P3 models directly. An example is Dell Optiplex GX1 that would take up to a P3 500.
More ram may help but be aware that many older machines often have limits on how much they will take. I think the Dell above will only take a maximum of 3 256 MG PC100. Other older Dell models will only take 2 sticks of 256. Even if they made 512 ram sticks that would fit, the machine won't see them. Some old machines may only see 128mb or smaller sticks.
Yes you may have to upgrade teh BIOS to upgrade the CPU.
Depending on the machine in question and where you can get parts, it may be cheaper to buy a whole new computer.
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The only thing George Orwell got wrong was the year.
The Ogre's Fiero Cave (It's also at the top of every forum page...)
[This message has been edited by theogre (edited 06-07-2004).]