cpu mhz is the main factor affecting emulation speed of Chankast. more mhz means more fps. compare screenshots of dc graphics to something like pc far cry or stalker to see the reason why. we all have wizz bang graphics cards with heaps of cool features but it won't make a scrap of difference if your generating graphics for a system which doesn't make use of all the fancy features.
About overclocking your cpu. A 2.4ghz p4 will go to 3.2ghz easily enough with the right cooling/motherboard/memory. There's nothing wrong with overclocking your cpu so long as you read all the relevant info, and don't try anything unrealistic. I have a p4 3.2 clocked to 3.7 with an aftermarket Jet4 fan/heatsink. it never gets turned off and there has never been a problem. I read that other people have 3.2's running at 4.1 with water cooling. I don't know about other cpu's, but Northwood P4's have a thermal limiter circuit built in to the chip. When the cpu goes above a certain temperature, it automatically underclocks itself till the temp returns to acceptable levels. This makes it impossible to fry the cpu through overclocking. you can fry them by raising the vcore voltage by too much though. you can also fry your motherboard and/or memory too. the best way to overclock is to look at overclocking forums and see what other people's results are with the same/similar hardware. I've never had a pc that i haven't overclocked, and i now buy components that are better suited to overclocking. I've never killed anything due to overclocking and my P4 was overclocked within one week of buying it. cpu's are just like any other electronic component. they are built to certain tolerances. when you overclock all you are doing is taking up the slack. there's a heap of old wives tales about overclocking and how 'dangerous' it is but in truth 99.9% of people who overclock do no damage whatsoever. the other 0.1% did not do the research required before attempting it. in fact you will find it difficult to find people who have killed their pc through overclocking. Intel obviously don't want you to overclock your 2.4 to 3.2, because they get a lot more cash if you buy the 3.2 instead.
Having said all that though, if you are not prepared to do a bit of reading and learn about the art of overclocking then my recommendation is not to attempt it. If you are the type of person who likes to click before thinking then just be happy with what you have. For people like myself though, it's like a free lunch. It cost me $60 Australian for the Jet4 cooler and i gained 500Mhz.
BTW. I also have an Asus P4P800 motherboard and kingston 3200 ram. The P4P800 is a great board for overclocking because it has all the relevant bios settings. In fact thats precisely why I bought it.