Re:Why bother with Mozilla? (Score 1)

IE 5 supports 70% of CSS 2 (last I heard) but as you say, it's not really solidified yet, so Microsoft reckon they won't bother trying to get support up to 100%, maybe 95% at best. (I'm reliably working on hearsay here BTW)
I suppose you could check out W3 for more info on CSS 1, 2 and (sigh) 3. (I really would rather if people got serious about standardising "standards" these days).

Mozilla M14 supports CSS rather well as far as I can see, which is already a big improvement on Netscape 4.x