Vista - No sound when external speakers are plugged in

I have been struggling with getting my external speakers to work on my laptop for a few months now. My laptop (Acer) runs on Vista and I plug my speaker into the SPDIF jack on the front of my computer. When I plug the speakers in a bubble pops up saying "A Jack has been plugged in." but there is no sounds. There are no little red x's on my little speaker icons and it seems that the computer thinks that the speakers are working just fine. If I hook my speakers up to my iPod they work just fine so I don’t understand why the won’t work on my laptop.
I have very little knowledge about computers and would love some help on how to fix this problem.

Please and Thank you!

What model Acer? What model speakers? How old is all this stuff?

My laptop is a Acer Aspire 5570. I bought it mid 2007 if memory serves me right. The speakers are little SONY ones. I don't remember there name but on the side it says Active Speaker System SRS-M30. I bought them around July of 2008.

I found the sony driver download site but Sony does not support the drivers for downloading.

esupport.sony.com/US/perl/swu-list.pl?mdl=SRS-M30&region_id=1

copy and paste this with http:// in from of it, don't use the www. in fron of this.

There was no CD or need to install these speakers so would there still be a need to look into trying to update the speakers. Sorry I am not good with computer so I don't really understand what a driver is and how it would help my speakers to work.

I am not sure about that. I was just seeing of the option for a Vista support driver. It is hard for me to offer help as I am not sure what level of information you know about how and what to set up your system for working of audio set ups. It appears that you have some option in the audio not established for external speaker hook up. That could be a bios or configuration setting for the audio settings. When you reboot with the speakers hooked up, the system does or does not recognize that you have external speakers hooked up?

When I restart my computer with my speakers all hooked up there is still no sound.

If I go to the sound setting and under the playback tab there is a green check mark beside speaker and it says "working" but still no sound. Also the Realtek Digital Output says "working", too. I don't know if either of these refer to external speakers but maybe it's helpful.

The SPDIF is a digital source, are the speakers you use having a midid plug?

No, it's just a regular headphone jack. The computer's specs says "headphones/speakers/line-out with SPDIF support"

Lets start here. At the bottom right hand of your computer screen, there is a speaker display (icon). Right click on that and select playback devices. If there is no speaker display then go to control panel and select sound then open that. There will be a window that opens and gives you a selection of what device is being used by a green check mark, the others will be a red arrow. What is checked green and what is red?