Sound cable

I have a sound card “BUILT-IN ON MOTHERBOARD” with [out,in, and mic.]
When I plug the two speakers into the “OUT” they do not work
but when I plug them into “IN” they will work. I
have Windows XP Home. Do you know what could be causing this?

1) Motherboard k7s5a socket “A” with AMD CPU 2200+ 512MB MEMORY.
2) 120GIG MATOX,
3) 56X-CR-ROM,
4) 48X12X48 CDRW-COM

Sound cable a big block plug w/ [pin 1 red], [pin 2 and 3 gnd.], [pin 4 blk.] from cd-rom
to motherboard end is samll white plug w/ [pin 1 red], [pin 2 and 3 gnd.], [pin 4 blk.]