Hello. and welcome. I think that i can help you out a lot. first of all, dont listen to this:
The move from 4X to 8X on an AGP textural graphics transfer will be minimal as the textures on your card will be stored on the video board's ram. Thus AGP 8x vs AGP 4x is really of minimal benefit even with 128MB of onboard dram as your video card will necessitate you dropping the quality down to a 128MB level anyway.
AGP Textural transfers were created at a time when most video boards had at maximum 64 and usually 32 or less MB of on video board dram.
This necessitated a method of transferring the graphics textural data quickly and with a proprietary interface. Thus AGP was created.
If you look at the PCI-e standard you will not find the textural transfer as it is now realized that there is no need for such a transfer with 256/512/1GB of dedicated video ram that is now faster than the system ram.
especially as your budget is limited. 8X agp means that the transfer rate from GPU to CMP's and to Screen is twice as fast as 4XAGP (basically), so there will be a DEFINITE increase in performance, and 8X AGP cards are newer, with a lot more memory, also ddr or gddr3 memory. so YES IT IS FOR SURE DEFINITELY WORTH IT TO REPLACE MOBO. YOU DONT REALLY NEED A FULL SYSTEM REPLACEMENT EVEN THOUGH YOUR PROCESSOR IS A BIT SLOW, YOU CAN GET SOME LIFE OUT OF IT. (cough...OC!!!...cough)
Anyways, I have found a large list of Socket 478 mobos online that your P4 2.4GHz 478 processor will fit in with 8X AGP slot each. (my recommendations are in the numbered list (whole list shows every one))
THE WHOLE ENTIRE LIST ON THIS PAGE:http://www.newegg.com/Product/Produc...TTR22=&ATTR23=
MY NUMBERED LIST (get #3 mobo, it is awesome)
1.ECS 648FX-A2: A good choice, though not for OCing, good for everything else
2.MSI PM8M-V: A solid mobo, good for just about anything
*****3.(THE BEST FOR SURE BUY THIS ONE, BUY THIS ONE)
ASRock P4VM800: The best, my personal favorite, i would buy this one. it has GREAT OCing features and an extensive Pheonix BIOS. A lot of reviews on newegg confirm this with many customers daying "great overclocking features, powerful but also easy-to-use" which is also good for you as you are starting out*****+ it isn't very expensive @ that newegg page
THE ZALMANN 9500 is an amazing heatsink, and it is almost as good as average watercoolong, but it is more expensive than most other heatsinks. I also have a list of good heatsinks, from cheap to expensive: Heatsinks
BUT MY cheap RECOMMENDATION, which is on that page, is for sure the
TR2TT TR2-M12 80 x 80 x 25 mm Ball Cooling Fan - Retail @ ONLY $9.99!!!
Listen to this review:
Reviewed By: cheap_overclocker, 2/11/2006 8:14:32 PM
This reviewer reports that his/her technical understanding of this type of product is high and has owned this product between 1 week to 1 month.
"Great for the price
Pros: Does a pretty good job, better then stock. It runs my overclocked P4 2.53 Northwood (over clocked to 3.0) at 53C max load, and 34C idle. I did polish the bottom with a metal polish and used artic silver 5, I would recomend a feash batch of artic silver, mine seemed a little extra gooy then the first time i used it. It is a solid hunk of copper, the fan isnt noticable and its a great value"
The others on that page are a bit better, look at the product, price, and reviews, but you can see that this one is a bargain
As fot the thermal paste, NOTHING BEATS Arctic Silver. It is the BEST. It really pwns all others, and you will never appreciate the importance of thermal paste until you see the effects of this stuff. You can find it herearcticsilver5
Finally, i got a list of nice memory, both low latency and fast types, balanced, not cheap crap or expensive diamond plated ram:http://www.newegg.com/ProductSort/Ca...sp?Category=17
i recommend the CORSAIR ValueSelect 512MB 184-Pin DDR SDRAM System Memory - Retail link @ http://www.newegg.com/Product/Produc...82E16820145026
Well, theres all that i have. good luck on your system rebuff!