Right combination of cables

I'm trying to get out as much as possible of my "mixed" system setup. System includes TV - RGB Scart (2) (Will be soon upgraded to Panasonic Plasma TV (37')) Digital TV Tuner - RGB Scart (2), Optical out AV Receiver (Cambridge Audio Azur 540 R V 2. - Optical in/out, Coax in/out DVD Player (Pioneer DV 350) - Coax out, RGB Scart out Speakers (2) Usher S520 My system is far away from perfect but this is the situation today. At least the AV receiver and speakers are good quality as well as the DVD player even if it is an older model. How should I connect these together and what kind of cable should I use to be able to get out the best performance (picture/sound)?