Reply to Studio monitors, soundcard & DAW question

Sup!

Right, just a question i need some help with related to my studio gear.
I have, a G5 mac, running Logic Pro 8, KRK Rokit 8's.

And I'm currently running 1/4 jack from my monitors, to phono into a 'phono to mini jack adapter' into the headphone socket on my G5.. (yes I know, its terrible isn't it?)

And basically, for one, i dont believe that what i explained above, is anywhere near the best way to use my studio monitors, I have Traktor and the Audio 10 soundcard, is it best to use that to run my monitors and mac?

Trouble is... I have a MBP 15", (i use this for traktor) .. but i just havent been able to afford to get logic pro 9 on this yet, so just using my G5 and logic 8. How ever, i cant run traktor on my G5 because it requires core duo processer etc, im just believeing, can I still JUST use the Audio 10 soundcard with my G5?

If so, please can someone explain how to set up my monitors and G5 and logic to run with the soundcard, and also, what cables to use. I use XLR to TRS/1/4 jack for my monitors to my mixer, when im djing.

Hope someone can help!
Let me know if i need to explain anything more,

Thanks!