depending on if you notice or not
probably wont get really high i don tthink, but back in the day a 200mhz increase was DAYUM NICE
...nowadays its like if you have less than 400-500mhz oc, its not given much consideration lol
OCing an athlon 900 is a good start, the "pencil trick" is relatively easy to do. Make sure you have good cooling on your cpu! Watch your temps closely, Increase frequency or multiplier slowly, add vcore in small increments to get system to run stable,Be very careful as this stuff is addictive and will consume all your free time!lol
It depends on your motherboard how you have to change FSB/multiplier etc. Some have a overclocking menu inside the BIOS others use jumpers and a few don't have anything at all.
Just make sure your CPU temp stays below 60-65C.
My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on