[adamdb]

As suggested, I would definitely hook it up to an analog port and do the comparison as shown. We tried to use a homemade IR sensor two years ago that had similar on/off voltage ranges and apparently the "off" wasn't off enough for a digital input. The reading from the sensor never changed when connected to the digital port. We ended up not using the sensor as it was a last minute thing and we didn't think to hook it up to an analog port and try it that way.