Ok, most people have commented that the Gamecube is good and underrated, but the games are mostly Arcade style, 'kiddie' games. And alot have said that Xbox look better for graphics. They have said that you may get 5 decent games on Gamecube compared to one totally blow you away awesome game on Xbox.
Here is what people have said over at the Portnoy forum:
I faced the same question and ended up with a Playstation 2. When I got around to having enough free $$ I bought the XBox as well. I don't even considered touching the PS2 anymore, the XBox blows it away.
The Xbox graphics are *insanely* better, even with just a RCA connection, if you use the svideo or high definition input they kick all that much more @$$
The sound is what really blows me away since there is in-game dolby digital encoding for surround sound. try turning around as someone is talking to you and the voice pans in full 3D around the room as you move, relative to where the person who is talking is. It's *damn* sweet. If you have a surround sound setup there is no way any other system would even be worth thinking about.
As far as the game selection goes I think the "PS2 has more games" argument is somewhat full of crap. I have 15 or so PS2 games, and almost all of the ones I like are also on Xbox and look better there. Plus any new games worth owning are coming out on all platforms. PS2 may have more, but other than Grand Theft Auto: Vice City, I can't think of any I couldn't get on Xbox
AND
Well, I own all 3. Here's my 2 cents. GC is just plain dead - period.
PS2 has a lot of games - mostly with PS1, but who cares? Are you gonna buy PS1 games to play on your new latest and greatest PS2? Nope. Besides, the system is showing it's age - in computer life, it's an old man. Yeah it's got a lot of cool games, and a lot of current and future support, but it's still an old man.
XBOX- this just plain freakin' rules. Just look at what you get for $179.99. A hard drive music ripper, an insanely fast CPU and graphics chip, Hi-Def support, in game Dolby Digital surround (this alone makes it worth buying), a slew of connection options, widescreen T.V. support, and a whole bunch of current and future games, some exclusive to XBOX because of it's power, that will just be light years ahead of anything current. Add in the hottest LIVE support on earth and you've got a no-brainer.
Really, the XBOX is the way to go IF you are just now buying a system. If you do buy an XBOX, buy it now before Micro$oft starts producing the system with cheaper components. They've said they plan on doing this to keep costs and profit losses down. Make no mistake, the XBOX has some pretty nice premium components. Who knows what performance hit it'll take when they scale back the parts.
Here is the link to the thread if you are interested in some more opinions:
http://www.mikeportnoy.com/forum/tm.asp?m=228807&p=1&tmode=1&smode=1