You mention a choice of S-video or VGA so I presume the PC won't be permanently connected to the Viera as both sockets are front mounted, though AV2 SCART on the back will accept S-video.
Given those two choices it must be VGA... S-Video will look blurred and out of focus you'll probably have a hard time even reading the text because of the low picture quality. I've tried S-video on a couple of different laptops and on a couple of different TV's (Not Vieras though) and on all occasions the result was extremely disappointing.
Go with the VGA socket on the front, if you want your PC permanently hooked up to the TV then I guess you could try feeding the component in using a VGA to component cable.
I should have explained more clearly. I will be using my pc to play dvd's and all other media files, maybe some gaming.
I was having trouble finding any info of which would give a better quality picture between the vga or s-video cable.
I have no problem with buying a stand alone dvd player and using component connection but thought I would try using my pc and saving a few bucks first.