how do I get HD streaming using Netflix disc on PS3?

[quitemouse]

I have the old fat 80GB PS3. My internet connection is
15mbps cable modem, which connects to my router and
than to the PS3 via wired ethernet port. Using Speakeasy
speed test, I verified that my PS3 is getting 15mbps speed.
The PS3 is connected via HDMI to my LCD TV.

When the Netflix streaming disc arrived, I was hoping to
finally see HD streaming. However, I haven't been able
to figure it out yet. When I choose a movie that has the
HD logo, it doesn't play in HD. The PS3 swtiches to 480p
resolution(as shown by my TV's own on-screen info, which
shows incoming signal as 720x480). When I stop playing
Netflix streaming, the PS3 reverts back to a 1920x1080
signal to the TV.

Can someone please help me figure this out? Thanks!