Turn off noise reduction?

When shooting in daylight with my 510 at low to medium ISO, will I get improved image sharpness if I turn off noise reduction?

It seems as if I read that suggestion somewhere, but for the life of me cannot recall where.

Yes, you will. I would also shoot in RAW and turn off the noise filter.

Actually you won't get any difference in image sharpness in daylight if you turn off noise reduction. Noise reduction is a different technique than noise filtering, and on the E-510 it only activates with exposures of at least 4 seconds, I think even longer at ISO 100. I leave my noise reduction on since I find the camera does an acceptable job at dark frame subtraction.

The noise filter is what you should be most concerned with - it will swallow up a lot of detail in a photo if it's too aggressive, and the E-510 is pretty aggressive with it. I keep mine off.