how do you choose a gd speakers? i'm currently into soundstream products.

http://soundstream.com/components-picasso.htm
http://soundstream.com/components-xstream.htm

among the 2 component sets(for front) above, which is better? how do u c the frequency? 72-20kHz. the lower the frequency(72kHz) the better?


http://soundstream.com/speakers-xstream.htm
http://soundstream.com/speakers-tarantula.htm

what about the 2 speakers(for rear), which is better?

i heard i need an amp wit it too.... will a 2 channel amp b OK for it? wat RMS do i need for that?
will u suggest a complete set of system for me from the above component set n speaker with an amp...
http://soundstream.com/products-main.htm

cheers