No problem. Replacing the CPU is just like plugging the PC into a different power socket in your house. The power will come from a different source but there's no way that the PC will 'know' this.
What on earth am I doing tonight! I saw 'cpu' but read 'psu'. (I've not touched a drop, honest!).
The analogy, above, is total b0ll0cks but the answer remains the same. Replacing the CPU shouldn't do anything nasty to your PC, although you might have to check that the BIOS is set to the correct frequency for the new CPU. (Well, I think that's right but it's definitely 'one of those evenings' tonight!).
maybe ..... maybe not .....
what you considering ..... tennis ball .... cricket ball .... football?
generally it's not a particularly good idea (in my opinion)
motherboards tend to accept a certain family of processors
mine is fitted with a 3.6 p4
it will only work with 3 -> 3.8Ghz processors (if you could find one)
The speed difference between the top and bottom proc is more academic than detectable (unless you are encoding video or similar)
a dual or quad processor needs another generarion of mobo - memory which is 3 or 4 times faster...... the only bits that are re-useable are the floppy and DVD (�30 the pair!!)
the case will probably be reuseable - but will probably need a couple of bigger fans .....
moore's law states that PCs double in speed every 12-18 months .....
the only meaningfull upgrade is likely to be extra RAM (and more that 1Gb on a single core machine is a waste .....
Motherboards and CPUs are built to work with each other, and the technology moves on hand in hand. A motherboard from say 2005 will take processors that were around in 2005.
And of course it is almost impossible to buy a new CPU that was being made in 2005, nobody makes them any more.
You cant just take a modern fast CPU and put it in any motherboard. Even a motherboard a year old may not be able to take a modern fast CPU.
So you need to find the documentation for your motherboard, and find out EXACTLY what CPUs it will take.
Of course you may find that your motherboard already has the fastest CPU it can take and you cannot put a faster one in.
One option to improve the speed of a PC is to replace the motherboard, CPU and memory, but then you are getting into a major upgrade.
I would do as ACtheTroll says and stick with what you have got and save for a whole new PC.
You should post the model of your motherboard as not only is the socket type important but m/boards only support certain types of cpu and intel have launched core2duo and 45 nm cpu's the last year or so