I have a dual-boot home-built P4 machine at home with a Logitech wireless multi-media keyboard. Under XP, the device functions as a standard 102-key keyboard. None of the extra buttons work (mute, volume adjust, etc.) Under Ubuntu, most of the keys work as designed (and this was autodetected during installation. I have not done any post-install customisation of the keyboard). I can mute volume, adjust it up/down, scroll windows with the little scroll wheel, etc. Nearly all of the extra keys work under Ubuntu that XP ignores. I could install the special software Logitech shipped with it to make those keys work, but it's slow enough already under XP without adding extra software to run. The machine is limited by motherboard design to a max of 2 GB RAM (which it has). Under Ubuntu, I very rarely see any page file swapping going on, but XP swaps frequently even with no applications open. Windows 7 better have superior memory and process management if they want to run in a low-RAM environment.
