For the past 10 years, I've tried many Windows boxes & laptops (Win ME, Windows 2000, Windows XP, and now Windows 7). Coming from a unix background (and especially vi/vim), I needed to have the Caps Lock key mapped to Ctrl. I've tried numerous apps to do this, but they all seem to fail at the task of using the Ctrl function (mapped onto the Caps Lock key) to incrementally select additional individual files in Windows Explorer, and in holding down the "Ctrl key" (mapped onto Caps Lock key) to drag/copy the selected set. It was a relief to know that SysInternals Ctrl2cap 2.0 is still being kept current, and now works for Windows 7. It has always been free. Just wanted to save others the half-day that I always spend rediscovering this whenever I start using a new machine.
What I said about other key remappers, and Caps Lock not properly behaving as Ctrl when Ctrl-dragging files to copy...that's when I use the touchpad. I've been using Ctrl2cap for so long, I can't remember if it's the same with the mouse.