In the broadest sense, yes, lower temps are generally better. Some styles (Belgians, hefeweizens) will be missing certain fruit esters that are important to the style if the temp is too low, but those are the exceptions rather than the rule.
You'll usually get the cleanest results from fermenting near the bottom of the recommended temp range for your yeast strain. You will tend to get very slow ferments and possibly poor attenuation if you go below the recommended range by more than a degree or two.
If you have temp control, a good rule of thumb is to adjust the ambient temp to the low point (or one degree below) of the recommended range for your yeast strain. Active fermentation will be a few degrees warmer than the ambient temp.
Bottle conditioning: Robust Porter
Drinking: Saison Dupont clone, tripel
Coming soon: Columbus APA, Rich Red ale
Last edited by cweston; 03-30-2007 at 12:48 PM.