How necessary is it to keep your Linux install up to date with the latest release of the distro you're using? I know some distros (Ubuntu, PCLinuxOS, Sidux...) have incremental upgrades, where a few mouse clicks or terminal commands will keep everything up to date. But other distros (Slackware...?) lack that feature. Is it okay to stay with older packages? Is whether you're using Linux for a desktop PC or a server a factor?