PS3+TFT, but no sound. Help appreciated.

First of all, hi guys. I've read here for a long time, but never registered, as with my admittedly limited knowledge, it's not like I could help anyone, and the forums have always answered all of my questions.

However this time, I'm stumped. I've tried all the suggestions so far and come up with nothing

This is the situation: I've bought a PS3 which works fine when hooked up to my crappy TV through the SCART. But of course I want to take advantage of my TFT so I hooked up the PS3 to it using a HDMI-DVI cable. The picture works fine and dandy, no complaints.

The problem is the sound. I used the standard red and white AV cables that come with the PS3 to connect it to a speaker and set the PS3's audio configuration to the correct setting (the bottom one that has the exact picture of the cables I'm using).

But I still get no sound whatsoever. Since everywhere I read I seem to see people with the same problem having it fixed by using the AV cables the way I'm using them, I'm simply stumped. So I hope some of you helpful souls can help me solve this, and get sound, as otherwise my options are either an extremely crappy TV with sound or a TFT with great picture and no sound.

Thanks in advance