Ya,the LNB looks the same( not sure it's excactly same ) but u cant share the SD and HD with the same dish UNLESS u request astro to give u a dual-head-LNB so that u can connect both ur SD/HD cable to the LNB directly,no splitter is allowed. There're few types of LNB,single/dual/quad but at the moment i only see the single type.

Btw,watching HD in pana HDready plasma is really nice ( too good to be true actually ) but i cant really see the diff between 720p and 1080i,need to change spec maybe Hopefully more and more HD channels is coming soon.