I just bought lightroom and have never used it before. I want to look at some tutorials at setting it up before I start using it. the hard drive on my laptop is nearly full and I am in the process of saving all my iPhoto libraries to an external hard drive. In setting up a catalogue is it beer to have it on the hard drive (which is almost full to capacity) of my laptop or on an external hard drive to free up some space?
It really doesn't matter where the catalog is located. There was a comparative study done a while back and it was determined that there was no performance hit from having the catalog on an external drive.
If this is the study you mean, the conclusion is that it doesn't matter where the photos are; ideally the catalog file itself and associated previews go on your fastest drive.