Considering that it only takes an inexpensive adapter to convert from VGA to old-school component video (the yellow plug) or SVideo, my guess is that it's probably no biggie to do the conversion from VGA to YPbPr, either. I could of course be wrong, but this is my guess (I also note that my TV has a VGA input that you can put an adapter for YPbPr inputs on; the opposite of what you're doing, but it seems like the conversion isn't involved).
As for how it'll look on your TV, that's going to depend entirely on the TV, how well it handles that input at high-def (versus, say, a pure-digital HDMI input), and maybe even how good the cable is.