Mark
I have a cube, but I play on all three systems (ps2, xbox, and cube) often. THEY ARE ALL GOOD PLATFORMS, let the games that look most appealing to you dictate which platform you get.
Some game cube games are in 5.1 (Star Wars Roque Sqaudren, Need for speed, and a few others)

LIFE IS SHORT.
DON'T BE A DICK.