I dont know about the switchbox, but i can say this about cables, i have taken 3 dollar audio cables and used them for component video, and yes the quality was worse, but it wasent that bad. still better than composite. and i look at the cables my PS2 uses all three together are about the same...
I guess i should also mention Dan that I am making these comparisions on a Toshiba 36HFX71, the toshiba's have the ebst line doublers I have ever seen so that will undoubtedly play a role. still on smaller sets like a 32 or 36 the difference is not night and day especially if you have a set...