You could also get an Athlon with a 200mhz bus. (I.e. Athlon 1400(200)) It has a bigger cache and may have some advantages because of this. However, the Duron 1.3g (Morgan core) has hardware pre-fetch and SSE compatibility, which would have some weigh against the Athlon. The Athlon will also consume a lot more power and require more cooling.
Just a few thoughts.
All errors are undocumented features waiting to be discovered.