Ok, for a long time I`ve been looking over diferent forums and sites for a solution to this. The other day I decided to change mi SbLive! MP3+ from PCI3 to PCI5 (which fisically shares the IRQ with my HPT raid controller) and since then no cracking is generated anymore!
My mp3 music runs smoothly as it does over 98se!
BTW, I used to change all values in my BIOS (I have a Abit Kt7-raid) with no luck. The only thing which improved but did not fixed it completely was setting PCI Latency=0