there is no real difference. the thoroghbred starts with 256k of l2 cache, whereas the thorton is a barton (512k) with 256k disabled. i would think the thoroughbred would clock better, but im not sure. the fastest axp if you are overclocking is either the XP-M 2400+ 35W or the XP-M 2600+ 45W. If you are not ocing, the fastest is the 3200+. The 3200+ is clocked at 2.2, the mobiles will usually hit 2.5 on good air. also, the mobiles have unlocked multipliers, meaning they are very easy to overlock. if you end up buying a new mobo, i would reccomend the abit nf7-s v2 (not the nf7-s2). another answer to your question: barton is the fastest k7 per clock.