Just wanted to give you guys an update:
I had a couple of LOLA senders / receivers laying around (I never used them when I ordered them or they came free with other stuff). So I went to the local MicroCenter store, bought 2 pairs of powered speakers ($6.99 each), then I went to Walmart and RadioShack and got me a couple of RCA-to-mini jack audio cables, as well as a couple of mini jack male-to-male connectors (receiver to speakers connection). All in all - about $15 worth of stuff.
Then I connected both wireless senders to the sound card (using an audio signal splitter), and followed your appliance module idea, created the required macros, timed it right, etc. I tested the sender / receiver to speaker connection prior to adding the appliance module, it worked, and then I added the final touches. So far I have both sets of speakers running, one in the garage ("welcome home" / "have a nice day" trigerred by the garage door security sensor), and the other one near the back door / kitchen area.
The mechanics are working perfectly, however I must say the quality of the wireless sender / receiver is questionalble, at best. In the beginning all I could hear was static. I played with the senders locations and finally got it to where I can only hear static 10 times (major improvement compared to before) in 5 seconds. I can hear the message OK, but like I said, I am dissapointed with the wireless senders. Add cheap speakers to the mix and you get the picture. Of course, the cheap speakers are all I need, as long as static isn't present. I will keep looking for other transmitters / receivers, maybe I'll find something more reliable. I purchased the baby monitors yesterday as well, and I will start playing with that as well and let you know how it works.
Thanks again for your help!
[TTA Edit: Added WHITESPACE to improve readability.]