still seeking advice

[Part On!]

Hi All,
I really want to start off on the right foot. I'm willing to invest in the proper equiptment so that I put out the best sound possible. I went to a pc show yesterday, and, here are the specs on what I'm having built for the hoster program.
P43.0
1 G Ram
2 120 hard drives
2 52x cdrw
sbpl7.1
15" flat screen monitor

Is there a better sound card that I should get?
Am I better off with a power amp, or, power speakers?

My brother in law is a dj/kj, and he is using the old, barberic method of cd's. He's really putting a lot of effort into getting me up and running, but, he doesn't think that I will have enough outputs from the pc in order to link to the mic mixer. I'm also planning to use PCDJ for the music side of things. Any help that any of you could give me would really be appreciated.