you can only get more out the CPU by upping the FSB. i'd say you should be able to take it up to 3.2ghz. just watch your temps.
upping the AGP/PCI clock doesn't do much if anything. all it does is increase the bandwidth to those devices and in most cases the available bandwidth is more then enough. upping them too high can cause instability. when that happens to your hard drive, which is apart of the PCI bus, you can cause data corruption. not a good thing for trying to squeeze out a little more speed. which you won't see anyhow as it's too small.
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