I'm pretty sure your monitor will have to have either an HDMI or a component(although it is unlikely you will find a computer monitor with this input) input. As far as I know, the PS3 doesn't allow you to convert HDMI into DVI or VGA.
For sound, you can simply use the AV cable your PS3 came with. You can have to PS3 output video from the HDMI slot and audio from the AV slot.







