I am considering upgrading to a new MB, case and CPU. I am considering either a ASUS or ABIT board, with an AMD chip. I am leaning toward the Thunderbird, but would like to know the pros and cons of the other AMD chips also, such as the Athlon or Duron. I am not going to buy anything in the GigaHz range... probably more like 850 or so, mainly due to budget restrictions.

Any suggestions are appreciated!