HD Decoder

[HDTV Rookie]

Hi:

I have a Hitachi 43FDX01B HDTV as well as Star Choice. I have yet to see my TV using a HD Decoder. In order to get the Star Choice hi def stations do you have to purchase a decoder from Star Coice or will another brand work? I think the decoder is currently around $400.00 at (it was $900 when I purchased the TV) is this a fixed price or does the decoder go on sale periodoically?

I guess what I am wondering is if it is worth my while to buy a decoder now or do you think they will come down substancially in the near future?

Also does the decoder improve the signal on other stations or is it strictly for the 2 available stations that Star Choice broadcasts in HDTV.

Any help would be appreciated...

Bye 4 Now