p4 478 upgrade from celeron

I have low end Dell Dimension 2400 that is about 5 yrs old came w/ Celeron 2200. CPU-Z ids it as Northwood Socket 478 mPGA 0.13 um.

I am going to upgrade SDRam mem to max 2 gig & want to upgrade the CPU also. I just want some faster response for kids using pc to slow down their complaints to put off getting a new system for them now.

I am trying to find one in US. Some I have found do not id whether they are Northwood. They are avail as 400, 533 or 800. I think my MB is 400 FSB but not sure. Some of the 400 are more expensive, or are about the same price as 533 or 800.

How can I interpret model # or find out whether it is Northwood?

Should I limit my search to only 400? And, if I don't have any luck locating one, should I consider a Prescott?

Are you aware of any retailers with 478's in the box? Newegg only has 1 Northwood - out of stock.

buying old hardware can be more expensive, might as well buy a new system now and save a few $.
Pentium E cpus are really well priced and the 45nm version just launched. DDR2 Ram is also dirt cheap, don't waste money on old DDR400.

Pentium E 2180:
http://www.newegg.com/Product/Prod [...] 6819116052

Kingston 1x 1GB DDR2-800:
http://www.newegg.com/Product/Prod [...] 6820134114

MSI P31 Neo-F:
http://www.newegg.com/Product/Prod [...] 6813130129

That is 775, not socket 478.

i think its time to let go of that socket 478....

go with ebay its the best option. get a P4 HT thats the best you can get on the S478.

The only P4 with hyper threading that will work is 3.06GHz/533fsb Northwood P4. Dell did not update the bios for Prescott CPU support, and the i845 chipset found in the Dell 2400 is incapable of running 800 fsb P4s.
So, the only CPUs that work are the 400 and 533 fsb Pentium 4 Northwoods (and the older Williamette, but you don't want one, trust me) and the 400 MHz Northwood Celerons. I suggest getting a 2.4B Northwood. That's a 533fsb 2.4GHz P4. They're cheaper than dirt on Ebay. less than $20 for one and it should be a significant upgrade over your current Celeron. There's also the 2.66B for just a little more money. Anything higher than that just isn't worth the money, as the high demand for the 2.8GHz and especially the 3.06GHz CPUs jack up the cost substantially.