I got a Logitech keyboard/mouse a few months ago. At the time I had a fairly open desk and the receiver worked fine, even when it had fallen to the floor. Now, I have a more enclosed desk, with the tower, DSL modem, USB hub, external CD/RW drive all crammed in right there with each other--with the receiver on top. It doesn't seem to pick up quite as well, not battery related. I guess it's the interferance from other pieces, and being enclosed. If yours is in the open, it'll work from almost 10' away (mine used to). If it's enclosed and tight, might find a way to seperate it from other stuff, but I don't think high/low would be a factor. I plan to move mine out a little.