How to create a css rule for all elements except one class?

Wouldn't setting a css rule for all tables, and then a subsequent one for tables where class="dojoxGrid" work? Or am I missing something?

The safest bet is to create a class on those tables and use that. Currently getting something like this to work in all major browsers is unlikely.

The negation pseudo-class seems to be what you are looking for.

table:not(.dojoxGrid) {color:red;}

It's not supported by ≤ IE8 though.