Too much, even for me :D
I can never see the point in arms in a game. They're never well done, and just get in the way. Like Dave says, I've got my own arms, and that's more than enough. As for a wheel, I can't really get used to driving without one. It doesn't add anything, like the arms, but from a technical point of view, it actually has uses - lining up your wheel to that one for instance, which it very important if you set your wheel up as sensitive as I like mine.
GTP has my perfect cockpit. All extremely high detail, and with plenty of function. NR2003 stock is great too, but I never use that.
nK has a nice novelty one, which isn't all candy, but nothing a few buttons can't sort out - it doesn't detract from the game, yet is something funky.
Standard rF and LFS cockpits are appalling... as is GPx's same-for-all.