This under-40 buck chip works wonderfully with Lisa 64bit, and is amazingly energy-efficient: 45W (five stars at Newegg.com). It was supposed to have been phased out, but recent reports said: «Sempron will remain in active production and ship out until at least the first quarter of 2012, and possibly much longer» (Fudzilla). I had it overclocked by 20% in Windows 7 (!), but in Lisa I didn't hesitate to turn it back to factory specs, with no change in typical behavior whatsoever. Get it while it lasts. Perfect with 4GB 1333MHz RAM.