Audigy ZS or Audigy ZA Platinum

I have been running onboard sound from my Abit NF7-S v2 and i love it but, the computer i have to play on at CPL will use audigy 2 zs, so, i figured i'd get one to get use to the sounds. THIS IS SPECIFICALLY FOR HEADPHONES! I can hear every single thing in game from across the map and i was just wonder some things.
1) Are there any disadvantages to getting a sound card?
2) Should i get the Platinum ZS for the external box or just get the regular ZS?
3) Will my sound be less detailed?
4)Anything else

Thanks

Well other than price and it takes up another PCI slot, I can't think of any downsides on an aftermarket soundcard

The Audigy (not sure if all Audigy models have this problem) has terrible 44.1khz playback to the point where people complain that it sounds bad. If you listen to a lot of well encoded mp3's (or other pc audio formats) you may be dissapointed, but in reality unless you are really picky, it will probably be fine.

Audigy (any) = gaming
Audigy 2 ZS = movies
Chaintech AV-710 = budget music (setup guide for best SQ)
EMU 1212m = high-end music

Audigy2 THX 6.1

thats exactly what it says the tournament comp will use

what should i get