Soundhound

I would like to create some music with my computer. Can you recommend some good quality PCI card with many input/output and softwares? How do I get started? what equipments do I need? I am not going to do the recording at this time, but probably will in the future. I just want to create music and playing some sample effects from computer.

Is it possible to take existing CD and remix, modify it with computer softwares?

Is it possible to connect my PC with a digital mixer and operate mixer directly from the computer?

Thanks