GakValadep - Speakers are subjective to the listener. It depends what you like. Overall, I would say the majority of the people out there would agree with me when I say that the Klipsch ProMedias (4.1) are the best 4.1 setup (overall, I said) Now, some dont' like 'em, but lots of people do.
I have heard them cause my friend has 'em. The bass is freakin' amazing. Best I've heard comming from PC speakers. The sats are ok. I would say the midrange is lacking (lots of highs and lows) but it could just be me. Some people don't complain about the Midrage.
As for 5.1, I would say the Midiland 8200's. Though, I don't really have anything to base this on besides all the reviews I've seen and emails aksing people what they thought of 'em. I haven't seem them given a bad review, so I would probably say they are the best 5.1 setup on the market.
As for soundcards, the SoundBlaster Live! line is pretty good. I have the SB Live! Platinum and it suits me well. Does everything I would ever want it to do. Phillips (sp?) just came out with a new card called something like the "Aucoustics Edge" or something along those lines. I've never really heard about it, but I've read one review and the person who reviewed it liked it a lot. Just do your research and pick what you think is best.