you should be ok with a p4 2.6ghz or higher (try to finds the max you can) your board supports the 800mhz fsb so just shop around
3ghz P4 3.0E $83 on newegg
http://www.newegg.com/Product/Produc...82E16819116175
oh and use this HSF $13 on newegg
http://www.newegg.com/Product/Produc...82E16835186127