upgrading a 478. Could use some good advice.

I have the Asus P4c800e deluxe board. I got it with a cheap 2.4 celron so I could upgrade it later. I'm now thinking of upgrading and could use some advice. I've been reading alot about not upgrading and just getting newer systems and the difference between the northwood and prescott if you do upgrade. I don't really know which to do in either case.

If I do upgrade, what reasons do you have to choose between the northwood and prescott, and why do people say the northwood is better. I have the good copper zalman fan with quiet mode so I have some cooling if that makes a difference(my only issue may be power, which I need help to determing if I'm having an issue with also.) What was the real difference between the northwood and prescott. and how much of a good idea is it to get a new system. I can probably only afford a small amount at a time right now and I don't know what to even begin to look at with newer systems. I'm guessing by time I built it I would just have to upgrade again anyway. Or is it worth for the cost of a 125 dollar processor upgrade.

I will probably have alot of questions after this, so don't worry about lack of info now. I will answer any questions you have.

I have a 2.4celron, Corsair value select 512x2(2100), 2 sata 250GB WD 7500 rpm drives (stripe), 9800xt.

And is overclocking a good option to make up for the difference in newer systems with this sort of setup? One of the threads mentioned using lower timed 3200 I beleive instead of 500mhz ram. What is the gain compared to newer systems?

There is a 48 free ground shipping on the 3.4E. It's kind of tempting but I'm currious about this prescott northwood tradoff. I heard about it alot when they were first tested against each other but I never really got to hear what the real nitty gritty was I guess and am still curious what the details are on how to choose between them. And Is the E worth it or make up for anything in the prescott. I think it is the new stepping with the safetly features or whatever in it.