Does your Philips unit have any input jacks? HDMI or Optical, for audio?
What's the model number? We may be able to find out if its compatible with an external player (PS3)
Check the back of your Philips player for a port that says "optical"
(see top right of this picture)http://z.about.com/d/hometheater/1/0...igitalopt2.JPG
If you have one of those, a simple Toslink Digital Optical (Fiber Optic)
is all you need to run from your PS3 to your Philips for audio.
You will need to change the audio settings in the PS3 menu to Optical
and you will get core 5.1 audio tracks from Bluray movies (and PS3 games)
You wont be able to play the higher end 5.1/7.1 audio like
TrueHD,DTS-HD and Multichannel PCM though...those are restricted to HDMI connections.
If you have no Optical or HDMI input jacks,
I'm afraid you're going to have to step up from an all-in-one DVD player/speaker combo typically refered to as a HTIB (HomeTheater In a Box)...
To an AVR (Audio/Video Receiver) with new speakers (5 or 7) and a Subwoofer.
But I think you'll have to up your budget for that.
With an AVR you typically run all your players into the Reciever (XBOX,PS3,HD Cable box)
then run a single HDMI to the PJ or TV. The AVR extracts the audio and passes the video to your display