I upgraded my computer to P4 1.7 Ghz, but the motherboard didnt have an AGP port. Now I find a very nice one, from Intel, with 5 PCI slots, AGP, SATA, 8 USB ports. The only catch is that Intel recommends 512KB cache processors, mine, otherwise compatible, has only 256KB. I wanted to know if it is such a big deal, since cache is controlled by the processing unit, not the mother board?
and if the board says that it supports your processor then its okay. having a processor with more cache is always a good thing. this totally depends on how much you are willing to invest in your upgrade. you have said that you have bought a new board that has SATA so it must be a newer model and it might have costed you some serious amount. so if you think that its not the time to buy a new processor then dont buy it. but as i have said, a processor with a bigger cache is always good.
by the way does the board have PCI-X. actually if you want to have good re-sale value then you must buy a board that has PCI-X because it has replaced the old PCI which was parallel in operation. but if you have got the board in your hand and opened the box then its alright.