Is the Intel stock HS with its fan at a lower-than-12V voltage enough to quietly cool a 2.26 GHz Pentium 4? Undervolting or underclocking is not an option with my Intel motherboard. The other components (PSU, HD) are quiet enough for me.

If this is not possible, what would be a relatively simple alternative solution? I am considering getting that aluminum-copper Zalman and replacing its fan with a quieter one (probably a Papst, since they are the quietest ones easily available here where I live) - is that a good choice?

Sorry if these are stupid questions, but reading the reviews and tests at the main site doesn't really help with particular matters of this kind.

Do the "stock HS + lower fan voltage" experiment yourself. Get one of those $8 Zalman Fanmates and plug your HS fan into it. Lower the voltage and run a CPU load app like Prime95 and see where your temps max out. I *think* 7 volts on the retail fan with a 2.26 might not quite be enough. Depends on your case temp/ambient temp, CPU load etc.

A Zalman CNPS6500B-ALCU would certainly work and it mounts right on to the existing heatsink attachment base.