I'm no expert, but I don't think it makes a difference whether your using XP or any other does it? Can't you do it using your F6 and F7 button on your keyboard?
yes B00 is correct I think (I just tried it) and it alters the brightness, I love reading your questuions henrys thay are always precise , polite and well presented!
Dotty
xxxxx
P.S. makes a change from the rubbish we read. lol
Henry - if your using a laptop then you'll probably need to use the Fn(function) key as well - botton left. On mylaptop its the Fn +F7and Fn+F8 keys but on my work pc it's the F6 andF7 as Boo says.
actually I tried again and it is fn key bottom left and F7darker F8 lighter on my laptop lol, so B00 was right for the PC and Chillispice is right for the laptop. : ))