StevieWonder: I have to disagree with your statement about needing a newer antenna. HDTV Signals are sent over existing UHF/VHF frequencies. So, any UHF/VHF Antenna will pick up HDTV signals just as well as Analog Signals.
The difference is this: HDTV is an actual MPEG-2 Encoded digital video stream being spurted out onto a radio frequency. The receiver in your TV, TiVo, PC HDTV Tuner, HDTV converter receives this signal in a 100% digial form. This digital signal is far superior to analog because even if you have a marginal signal, as long as the signal stays constant you will have AMAZING picture. There is no such thing as snow on HDTV like on Analog channels that are broadcast. There is digital fade. If the marginal signal is intermittent ( due to obstruction, antenna movement, etc ) then you can experience what looks like a bunch of square blocks on the screen that don't match what should be going on on the program your watching.
With HDTV over the air signals, you will see NO DIFFERENCE when compared to Cable/Satellite HDTV signals... Except that it's 100% FREE! (If you have the hardware that is.. )
One thing to realize though when watching HDTV Over the Air (OTA) signals. Most of the local TV Broadcasters are VERY new to HDTV. You will notice hiccups from time to time depending on the local broadcaster while they 'fine tune' their systems. These hiccups could look like digital fade as described above, audio drop out while the video continues on fine, or the signal returning to an SDTV format (letterboxed) for a period of time.
Also, not all content provided by local HDTV broadcasters was originally recorded for HD broadcast and even though you're tuning to an HDTV signal and getting great reception, the show you're watching will appear with side letter boxing.
If anyone has any more questions, please ask away!
LK
**Edit: A great web site to see what HDTV channels are available in your area is
http://www.antennaweb.org/aw/Address.aspx ... I've punched in my address many times on that site without getting any additional junk mail. Just make sure to uncheck BOTH of the 'You may send me...' boxes before hitting submit. Also, keep in mind that even though the channel you're used to watching may be in the UHF range ( Channels 14->69 ).. The FCC may have assigned them VHF spectrum for their HDTV signal. The antennaweb.org site will help point that out as well.