AnandTech has a good article on the AMD roadmap.
XbitLabs shows that the overclocked Sempron 3100+ beats the Pentium 4 3.4GHz in a lot of tests as well as the very best Athlon 64's ! "Thanks to its clock rate, which is higher than that of any Athlon 64, the (overclocked) Sempron 3100+ outperforms the Athlon 64 3400+ as well as both Pentium 4 with a frequency of 3.4GHz!"
