Okay first off, don't get the cpu or mobo pizzathehut selected for you. This combo is overclockable to 3200 speeds (2.2ghz) with air cooling-
AMD Athlon XP Mobile 2400- http://www.newegg.com/app/ViewProdu...-103-439&depa=1
Abit NF7-S2G (says NF7-S2, but upgrades to NF7-S2G)- http://www.zipzoomfly.com/jsp/Produc...uctCode=240143
Abit is known for their stable motherboards. And if you are worried about overclocking with this combo, don't be. Lot's of people have done it and have been stable at 2.2 ghz. This hsf and hs is what I recommend you use to cool your cpu- http://www.newegg.com/app/ViewProduc...106-037&depa=0
That will keep everything nice and cool. All this is for about the same price as what pizza mentioned.