See my opinions/rants in an earlier thread concerning the nVidia drivers:
http://forums.anandtech.com/messageview.aspx?catid=29&threadid=1597495
I live with continuous flogging of my hard drive and occasionally need to click a second time on a link while browsing -- not what I want but I ignore these (no choice, really). Most NF4 owners have no issues with the nVidia drivers or fail to recognize the issues they have are due to the drivers. There is a broad range of possible problems which seem to be due to the drivers. Since you may have no problems or you may have serious problems, as Dirty Harry would say: "Do you feel Lucky?" You do your due diligence research and then you make a choice...
SpeedFan works well for me. The VNF4 has a temp sensor near the CPU and another near the chipset. I use the CPU temp to control the CPU fan speed (of course). The high and low fan speeds can be configured. Then, you specify the desired temp (28C in my machine) and SpeedFan will adjust the fan speed appropriately to hold the temperature at that setpoint. Of course, the setpoint must be reasonable; too low and the fan will be at max all the time trying to cool the CPU to the (unobtainable) setpoint.
With the setpoint=28C, the CPU fan speed on my machine is 1400 when the room is cool (72F), rising to 2200 when the room is 82F, all at idle/browsing the net. The fan becomes audible about 2800+. The fan speed will go to 3300=max at full processor load and the CPU temp will rise to 38-45C, depending on the room temp. All this info is for a 3000+ Winchester with stock AMD cooler and running Cool 'n Quiet.
The AMD cooler at full speed produces a whine/buzz which is obvious because it is louder than the Sonata case fan -- I wouldn't say it is loud, I had an HP which was FAR louder until I changed the fan to a Panaflo and used resistors to slow the fan speed
I mention the nVidia driver problems frequently because I wish I had known about them prior to choosing my new system. Only because then I wouldn't feel I had been sort of snookered.
I'm really pretty happy with the VNF4 and don't think I'd make a different choice if I were to choose again now. But it took a lot of fiddling with the nVidia drivers to get my system to this point - I've learned much more about drivers and their loading techniques than I ever really wanted to know.