Windows 7 - several questions on Media Center

hi everyone, i have some question on the windows media center, i'm new on windows 7, i was using windows xp before so i haven't touch anything about the windows media center, but just now i open it on win 7 and i found it is interesting and i want to have a go, are there any site that have some instruction and introduction for it?? as i try to go on it myself i just don;t have a clue.

also, i have look at some post here about the internet tv on media center, does this feature on support in US? as even i go on to the update in media center for the TV section, i still can't see any thing like internet tv, do this effect because i'm in Hong Kong?

finally, when i click on the tv function, it told me that the media center cannot search any tv turner (well....i don't have any tv card or something), i realized that i will need to have a tv card to turn on the tv function so i'm going to get one, are there any specify tv card that support media center? or just buy any tv card? usb one will be work or not?

thanks for looking at my poor english and i hope somebody can help me with it, thanks again~