RAM Speeds in variations

[SpaceMagic]

Hey all (but most likely CanadaRam, the resident RAM expert),

My PowerMac G5 has:

2x128
2x128
2x256

to make a total of 1GB.

1) I was just wondering if having so many modules was inefficient? Would just 2x512s be better? Or does it really make no difference?

2) Also, I'd quite like a little more, should I sell off the ram which is in there and get 2(2x512) = 2GB crucial sticks (or better in the UK?).

3) Lastly, is Crucial Ballistix (their "high performance" ram) faster?

Cheers guys,

SpaceMagic