I tried all the others first, and had problems with each: - Synergy is no longer free. Even the nightly builds are crippleware. - Mouse Without Borders swaps all keyboard and mouse like devices from all machines to the active one, which prevents use of an HTPC remote on my HTPC when slaved to a laptop. - ShareMouse considers preventing the mouse from switching screens unless Ctrl is pressed to be a premium feature, and nags the crap out of you about it. - MWB and ShareMouse both have issues with controlling games. ID has *none* of the above issues, and is completely free.