Logitech Z4 and Realtek ALC889

Hey guys
I am replacing my current cheap speakers with some Logitech Z4s which is as much as I can spend (£40). My current speakers are some cheap branded £15 ones from Comet. I am using my on board Realtek ALC889 HD audio atm. Sound is ok but could be better, so I want to know are these speakers good and will I notice a diff in sond or will I need to get a sound card?

The sound card I am looking at is the Asus Xonar DS, would this show a improvement over the on board with the Z4s?

Cheers

SRS audio sandbox will probably be the best sound card u can get

its a sofware driver like DOLBY and u can restore lost souind made from crap sound cards

plus improved bass