I have a Foxconn P9657AA M/board with a P4 3.4, the problem i have is it only has a max fsb of 1033. should i bother getting the best Duo core at that speed or just get a new mainboard. And here's the stupid question you came to see, will i have to up grade my OS from Xp or will i be able to use a Duo core with Xp...please hold back the laughter its been a while since i built this pc and ive fallen a little behind the times.
Windows XP Home supports multiple-core CPUs, so you won't need to buy a new license. Your board also supports a lot of Core 2 Duo's, which is good. As long as the FSB of the CPU is less than 1066, then you should be fine. The Q6600 would be a great chip that should fit.