those questions are designed to tell me whether or not your integrated or existing soundcard is of "good" quality.
after all, purchasing another soundcard when you already have a good option is like throwing money into the wind. money you could be using for those speakers.
"good" 5.1 speaker set is relative. what type of budget are we looking at?
some people consider good to be $200 or under in which case the 5.1 sets from logitech are very good value. to me my $1500 system is what i consider good and my setup doesnt use a soundcard. still other people do as i have done but with a budget of $500.
what it really comes down to is as i said....
what do you want to hook up to it? pc speakers? home theater speakers?
what ports do you need? optical out? 3.5mm jacks?
what is your budget for soundcard? what is your budget for speakers.
the more information you provide the better information can be given back.