Apex....oh god! I sold too many of those and heard too many horror stories *shudders*. Though for a few people it seems to run ok so far... and yes... the soundblaster extigy puts out digital 5.1 sound (I think it can do up to 7.1 though I'm not too sure). No wonder you're getting crystal clear sound pretty much.
Regarding the gaycube (lol, haven't heard that yet). Yes it's worse then ps2 or xbox but it's still pretty good. I don't play enough games atm to warrant the other two. Though when they drop in price again in anticipation of the other releases, I might pick one up. This has decent games too. Right now I'm playing True Crimes, streets of LA. Have to finish Need for speed high stakes, metroid prime, a give away disc with 4 old zelda games, and some other rpg I pikced up for 3 bucks (lost worlds 2 or something like that)