This spreadsheet should help you budget.
I said what I did about the 45nm quad because I read many posts on this site that many people were getting a max stable overclock of 3.5GHz or so o on the 9450 (with reasonable voltages). From what I remember that was a FSB limiter, so the 9550 should get around 3.7GHz with the same FSB. The extreme chips (with unlocked multipliers) seem to be getting over 4GHz though. I am by no means an expert, I was just relaying that your goal may not be realistic. I would shoot for 3.5GHz, and if you exceed that it would be gravy. Although I suggest that you get a better "expert" than me to give you advice on overclocking your future quad core chip since I don't even have one.
I said what I did about the 45nm quad because I read many posts on this site that many people were getting a max stable overclock of 3.5GHz or so o on the 9450 (with reasonable voltages). From what I remember that was a FSB limiter, so the 9550 should get around 3.7GHz with the same FSB. The extreme chips (with unlocked multipliers) seem to be getting over 4GHz though. I am by no means an expert, I was just relaying that your goal may not be realistic. I would shoot for 3.5GHz, and if you exceed that it would be gravy. Although I suggest that you get a better "expert" than me to give you advice on overclocking your future quad core chip since I don't even have one.