Your monitor should have DVI. For best quality use HDMI to DVI. FYI if you watch moves your PS3 usually drops to 24Hz which could hurt your monitor. Gaming should be fine.
Also for sound. It depends on what you are using for sound. (Line-in on a Computer, or speakers that have jacks built in them.) You can use multi-cable setups.
Like when I was at work. I used HDMI from my PS3 to DVI to my monitor. For sound I used the Audio/Video (Yellow, White, Red) cable with a convertor like this one
and plugged it into the Line-in on my PC’s sound card. Then I went into the PS3 settings > Sound and set it to Audio Input Connector.
Hope this helps.