HDMI to VGA? EEEEEW.
At least do DVI.
Just get a HDMI to DVI adapter ($~16), and hook up the audio via RCA jacks (comes with the PS3) to your sound source (may need a splitter for that). It's an adapter that plugs both RCA (red and white) into a single 3.5mm jack.
Total package costs about $25-45 US with tax.
Here's the audio splitter.
And the male HDMI to DVI
Also note that your LCD has to support HDCP or else it won't work. But it's definitely worth the quality.