Im thinking of getting a PS3 Slim and wondered if i can use a HDMI to Component cable with the PS3 and a Panasonic plasma with component in? or does it have component out?

Reason for not using the HDMI? TV only has two and they are both in use

Could you not just unplug and switch the HDMI cables around when you want to play the PS3?

Buy a HDMI switch splitter...

Duronic HDS3 Mini 3 Port Gold HDMI Auto Switch PIANO: Amazon.co.uk: Electronics

I use something similar!

thought about a splitter but had them before on scares and they never worked properly, and it just too awkward where my tv is to keep swapping them round just to play games

Mine works fine - I have 3 HDMI ports; 1st is for Sky, 2nd is for Xbox 360 and 3rd goes to the splitter, which is used for PS3, BluRay player and Popcorn Hour.