A word of warning
Don't buy a PcLine keyboard/optical mouse set. I've just taken back the second one with the same problem, which started in both cases after a month or so - main mouse function not working, although scroll and clicks were. Found it is very hard these days to run a computer just with a keyboard. Now got to get used to another different keyboard and mousing, having had to pay £15 more for them. Grrrrrr!