Which of these 3 processors is the best to get?

Intel Pentium 4 / 2.4CGHz 512k socket 478 Hyper Threading Technology 800 MHz FSB - RETAIL

or

Intel Pentium 4 / 2.53GHz Northwood 512K Socket 478 Processor 533MHz Processor Bus OEM

or

AMD ATHLON XP 2800 "Barton" 333 FSB PROCESSOR CPU- RETAIL

They are all $174.

IMO P4 2.4c Do you plan on overclocking? 2.4c one heck of a Cpu for overclocking.

I would forget about the northwood.
The 2800 barton and 2.4c are pretty close. It depends on what you already have for hardware, what speed of DDR you already might have laying around.
From the ground up between the two I'd go 2.4c.

If you have slower DDR (266 or below) go athlon.

Your going to have a cheaper system when your done with the athlon if you don't have a motherboard and use a Nforce2 than the P4.

They are close enough in performance though it really depends on the criteria above.

Athlon 1700+, Epox 8RDA (NForce2), Maxtor Diamondmax Plus 9 80GB 8MB cache, 2x256mb Crucial PC2100 in Dual DDR, Geforce 3, Audigy, Z560s, MX500

The ABIT NF7 v.2 at excaliberpc.com is $109 as well.

So both are exactly the same price.

I'm thinking of sticking with the 2800+ though because the NF7 v.2 has integrated Firewire.

2.4c without question.

Pay about $100 for the RETAIL 2500 Barton...
Mine is at XP-2900 speeds without modification to the chip, or added voltage. I upped the multiplier from 11 > 12.5 My heat increase was about 2 degrees.

Drop it into an ASUS Nforce2-Ultra400 board for about $125 (includes RAID, Firewire, SATA, 6 USB ports)


Amiga - The Original Power

I am a fan of Both AMD and Intel. So it depends on your budget and future plans with your computer. If price is an issue then AMD Baron 2500+ is the way to go as mentioned in previous post. It is a proven easy overclocker and with modern motherboards you can lock your PCI and AGP so those components don't overclock. Since you mentioned that you dont OC, that cpu is still good perfromance/price ratio. With OC get PC3200. WIthout OC get PC2700 LOW LATENCY CL2.
But to directly answer you question the P4C over the P4B. This to me is a no brainer since you will be using the Intel based 865 or 875 new chipsets which supposedly will upgrade to Intel's next line of Prescott cpu's (at least according to Asus)
If you go with the P4C with 865/875 motherboard you will have to and want to use PC3200 (CL2 recommended).
If you want to enable the DUAL DDR function in these motherboards you will have to use 2 sticks of RAM.

...patiently waiting for 10Ghz processors and immersible virtual reality.