buying advice shift registers

hi ben

thanks alot, this starting to make sense to me...
I'm just looking at the example with two shift registers, that's an code fragment:

void blinkAll_2Bytes(int n, int d) {
digitalWrite(latchPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
digitalWrite(latchPin, 1);
delay(200);
for (int x = 0; x < n; x++) {
digitalWrite(latchPin, 0);
shiftOut(dataPin, clockPin, 255);
shiftOut(dataPin, clockPin, 255);
digitalWrite(latchPin, 1);
delay(d);
digitalWrite(latchPin, 0);
shiftOut(dataPin, clockPin, 0);
shiftOut(dataPin, clockPin, 0);
digitalWrite(latchPin, 1);
delay(d);
}

Am I correct that shifting out has to be done twice because
there are two shift registers?

On another note, I'll be using 48 leds with 6 shift registers.
can the arduino power that much leds? If not, would it be possible
to light one at a time in such a high frequency that it looks like
they are all on?

sorry for all those questions...

best
yves