I have Realtek EMC 2.0 speakers, but they don't seem to work.

Everything is hooked up, but no sound comes out, any ideas?

make sure the speakers volume switch is up.
check your audio properties (often the little speaker near the clock) make sure ALL of them are turned up to max or where ever the hell you want them.
make sure the "main" or "master" and "wave" or "mp3" or anything like that is not muted. basically none of the "output" fields (save microphone) should be muted

Are these new speakers you just added to your system or have you had them all along and they suddenly stopped working?

@ rellikpd: I have turned everything to max, and still nothing.
@ bizob: They are fairly old speakers, but they stopped working after I installed some ATI drivers, so I will check that and see if I can fix it.

ok, I can't fix the speakers, but I am using a USB headset now.

Although anything is possible, I highly doubt your video drivers affected your speakers or sound card. If possible, borrow a pair of speakers from a friend and if they work then you know your speakers died on you. If you can't find anyone to lend you a pair of speakers
a)ditch those selfish jerks and get some new friends and
b)go to the store and buy a cheap pair for testing purposes, hold on to that receipt so you can return them.

If you really think it was the ATI driver install that messed up your sound you can roll back the driver or use a restore point to go back to a date when they were working.

Good luck.