wait for the k7 (Score 1)

It doesnt matter if it's a PIII or K7.
The G4 enebled with AltiVec will kick butt anyway.
Running at 400 will outperform the P3/500 with 25-200% in everything where Math is used like Speech, Image/MPEG, 3D Graph and Encryption.

For example:
-128bit permutation - very important in DES and other encryption schemes.
Altivec - 20cycles
MMX - 4cycles/bit = 512cycles.

-Median Filter (3x3) Replaces center pixel in a 3x3 window by median of sorted pixels
Altivec - 1.23cycles/pixel
MMX - 415cycles/pixel

AltiVec will rule!
Read more about it:
http://www.appleinsider.com/articles/9812/pcc-ro ad-map.shtml