A simple question with so many possible answers.

Frank and Paul have both given good advice. A Denon amplifier is always a good start, PMA-250SE, PMA-255, PME-350SE or PMA-355. They each offer a good starting point, sound decent and are reliable.

CD player? Buy new! A good make though.

Speakers? Keep it simple. A good two way compact standmounting type will give you all you need. (I'm picking up a pair of Usher S520 speakers myself shorty, as a back up to my system. A pair of those would suit you fine and work well with a Denon amp)

Cables? Something reputable. Second hand is usually good if you want to save money. (avoid QED Silver Anniversary speaker cable)