what shader version can your pc handle?
i know i've seen a few people mention their beasts, but i've seen way too many game developers on this forum with graphics cards so old that they do arithmetic by counting their fingers (if a graphics card had fingers).
julz
ps: when choosing what shader model you'd want to support if you released a game right now, choose as if your game can only support one shader model. i want to see what people think the best balance between looking good and wide compatibility is.