From what I understand, yes, you can use both of them together no problem. HOWEVER, because the 430 and 580 ex ii speedlites are only optical, if you have the 600ex it will have to be placed on optical signals, the radio signals wont work, which limits your freedom a bit with lighting because your flash will have to be in line of sight.
It is a little bit of a bummer especially since one of the huge bonuses of the 600 is the ability to use a radio signal. But hey, at least it works!