since nobody is answering your questions ill go ahead and step in here...
first off the processor. people should pick one of 3 options when it comes to the processor.
Pentium 4/ 2.4C GHz 800MHz FSB, 512K Cache.............136$
or
Pentium 4 520 2.8 GHz, 800MHz FSB, 1MB L2 Cache,..........160$
or
Pentium 4 550 3.4 GHz, 800MHz FSB, 1MB L2 cache ..........282$
the reason for this is that with the 3.4 (not 3.0 or 3.2) abit and asus motherboards offer the option to change the multiplier to 14 this reduces the processor speed to 2.8ghz (14 x 200fsb) this allows you to overclock the fsb much higher than you normally would be able to due to the 4.0ghz being more or less the "redline" of processor speeds.
the reason people want a higher fsb is so that thier ram can run at faster speeds (ram runs at 2 times the fsb) because if you buy ddr533 ram but leave your computer at the stock 200fsb speed. then the fastest your ram will run is ddr400. whereas if you overclocked the fsb to 250 then your ddr533 ram would run at ddr500 and your processor would be at 3.5ghz
(14 x 250fsb). if you got your fsb up to 266 your ddr533 ram would run at its ddr533 speed with a processor speed of 3.724ghz (14 x 266 ).
as to making the decision between the 2.8ghz processor and the 3.4 ghz processor.
keeping in mind that no matter what speed processor you get 4.0ghz is an absolute redline. people can run past that speed. but not very far and not very often(are people able to get a stable overclock that high).
with that said overclocking your 2.8 processor to 3.724 with a 266fsb is a huge overclock. you are getting nearly a whole ghz more. it is very possible that your 2.8 processor may run out of gas so to speak. and not be able to overclock that high leaving you to settle for a lesser overclock.
whereas overclocking your 3.4 to 3.724 with a 266fsb is a much lesser overclock and chances are that your processor will be able to push that minimal distance.
however. a less than high quality powersupply, motherboard or ram may be a limiting factor in getting to 266fsb.
with abit boards the vdimm voltage (voltage available to give your ram) many times is not enough for the power hungry brand of ram the person chose to run.
a great priced high speed low latency non power hungry brand of ram to get would be as they only require 2.6 vdimm opposed to most 2.8 thru 3.0+
G.skill (Samsung TCCD) Dual Channel Kit 184-Pin 1GB(512MB x 2) DDR PC-4400
http://www.newegg.com/app/ViewProductDesc.asp?description=20-231-004&depa=0
here is a good review on that
http://www.madshrimps.be/?action=getarticle&number=2&artpage=949&articID=244
many people seem to think ddr2 ram is much more expensive id have to disagree with them
ddr400-ddr533 patriot xbl is 220$ here this ram runs at 2-2-2-5 (the tightest timings) at ddr400speed and 3-4-4-8 at ddr533
is only 220$ here
http://www.newegg.com/app/ViewProductDesc.asp?description=20-220-033&depa=0
with the site info page here
http://www.pdpsys.com/products/PDC1G512G3200+XBLK.pdf
and the DDR2 533 CORSAIR VALUESELECT is 222$ here
http://www.newegg.com/app/ViewProductDesc.asp?description=20-145-526&depa=0
with motherboards sometimes people choose to run The i865 chipset mobos. these tend to be less desirable because of their smaller power mosfets. and can be a limiting factor to your overclock.
The i875 chipset mobos generally seem to have a more robust power circuitry.
and are the better choice between the 2.
as for power supplys. this is the most underrated part in its importance for overclocking. it is imperative you pick a powersupply brand that is know for supplying CONSISTANT power at the rated watts. as many merely list thiers PEAK watts which is nowhere near the amount they can consistantly supply
toms hardware lists 3 brands they would reccomend here
http://www6.tomshardware.com/howto/20030609/power_supplies-18.html
here's a site with great info on picking a power supply for your system needs
http://www.bleedinedge.com/guides/psu_select/psu_select_01.html
and here is the place to get the best rated powersupply for 110$ the antec true 550 ( the one on newegg is not the real one that one only has 24A on the 12v rail)
http://www.devhardware.com/c/a/Power-Supply-Units/Antec-True-Control-550/
last but not least the heatsink is a very important factor in overclocking your computer. you should pick one of 3 options when selecting a heatsink..
aircooled rankings
http://www.overclockers.com/articles373/p4sum.asp
watercooled rankings
http://www.overclockers.com/articles373/waterkit.asp
the thermalright xp-90 is the best aircooled heatsink there is. with a C/W rating of 0.13 it beats the top water cooler with a C/W 0.16
i recommend getting this with some artic silver 5 and a high output panaflo fan at
www.theheatsinkfactory.com
coming in 2nd would be the xp-120 with a C/W rating of 0.17 this is a good selection because with the bigger 120mm fan it can move lots more air with way less noise. the downside of this one being its uncompatibility with some motherboards. you can find this list at
http://www.thermalright.com/
coming in 3rd for its ridiculously low price 20$ for the performance you get is the Vantec AeroFlow VP4-C7040 For Intel P4 478 it ranks the same as the 2nd place watercooler with 0.18 C/W
http://www.newegg.com/app/ViewProductDesc.asp?description=35-110-008&depa=0
hope this clears things up for you guys reading