If anyone's interested in getting glitch-free playback working on hardware too old to have an HPET, you too can force the kernel to use your TSC as a high-res timer source with Jeff Hansen's patch here: <http://lkml.org/lkml/2008/10/10/235> It's probably best used only on a system that you know doesn't use ACPI or SMI for much if anything and which doesn't get 'tsc: clocksource is unstable' warnings. It's probably almost always safe on a uniprocessor: it's not as if the TSC can get out of sync with respect to anything else on that (well, it can get out of sync with respect to real-world time, but not seriously enough to notice in my experience). I'm using it here and it's working great. (Now my only problem is that my Ogg player is playing music over a saturated network link and is consequently glitching like crazy ;} )