No way to really gaurantee that the ram will all work together nicely. In general it is not a good idea to mix ram size/speeds, but you may get lucky and be able to use them all at the same time. Are they at least the same speed? If so, you may get lucky and be able to run them in dual channel.
As for the4 sticks, it is actually the memory controller on the CPU (not the motherboard) that is the problem.
Athlon64 cpus don't typically like 4 sticks of ram. There is a high chance that it will automatically underclock your ram to PC2700 speeds and bump you to a 2T setting.
Personally, I'd stay with 2Gb of ram at PC3200 1T settings. Since most applications wouldn't use more than 2Gb anyways, you'd be better off with fast 2Gb over slower 3Gb.