If you don;t want to spend all that much money to replace ram and processor and MOBO, then get a 423 to 478 pin converter, and a new 478pin processor, but don't make it overkill. A 2.2GHz is fine, since your MOBO will only recognize 2.0GHz maximum anyways. Here are two links to the products I stated above.
423/478 Converter-
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=14293&item=6726701574&rd=1
THIS IS EBAY BUY IT NOW, so just do this for $10.
Processor-
http://www.acmicro.com/PPmain.asp?IC=2303&Action=Mostrar&msk=PD
This is a 478 pin processor with the same 400MHz FSB that your MOBO recognizes. This one is perfect for its price ($116)
GRAND TOTAL- $130 with shipping probably
OTHER OPTION- THe other option is to buy a new MOBO, AMD processor, and RAM (DDR PC3200) Here are links, and I will give grand total for comparisons sake. GL either way, and I hope this info helps.
MOBO-
http://www.ewiz.com/detail.php?p=MB-K8NSU93&c=pw
This is new socket 939 technology, nForce3 Gigabyte MOBO, that supports the newer AMD64 chips and FX chips.
PRICE= $116!!!!!!!!!!!!!!!!!!!!
PROCESSOR-
http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=120421
This is an AMD64 3000+ processor (939pin), but I would go one step further if I were you...
PRICE= $155!!!
http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=120422
This is an AMD64 3200+ 939 Pin processor, and this CPU will kick all P4's asses except maybe the 1,200 "Extreme Edition" one...
PRICE= $194!!
RAM-
http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=85002-12
This is 1GB (2X 512MB) of Geil's Ultra series ram (GOOD RAM!!) for only $199!! I'd do this, but I will provide a link below for Mushkin ram (still very good ram!), but not Ultra series.
PRICE=$199!!!!!!!!!!!
MUSHKIN-
http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=140536
PRICE= $174.....!.....
TOTALS:
WITH GEIL RAM and 3200+= $520 or a bit less!
WITH GEIL RAM and 3000+= $475 or a bit less!
WITH MUSHKIN RAM and 3200+= $500 or a bit less!
WITH MUSHKIN RAM and 3000+= $450 or a bit less!
ANYWAY, GL and I hope this helps you decide what you need, or what you want. Weigh the advantages and disadvantages carefully, looking at your budget and need, and then decide only after lots of though (this is an investment after all) GL!