The component video will be just as good as the HDMI for HDTV, or it should* be. Once in a while (totally dependent on the box itself) the HDMI looks better, and once in a while the component video looks better.
You may consider buying an antenna right now. Free HD OTA. Even when you get the HD service with cable, if you are ever watching NFL, or Final Four, or Olympics, or network news, flip over to OTA for the best signal you can possibly get (better than any cable or sat service). All you need is a cheap coax to run to your ATSC tuner. Channels are national only, no EPSN or Discovery or History etc.
I recommend Target for one, you can try Rat Shack but your YMMV there.
Plug your info here to see what you'll get.
http://www.tvfool.com/?option=com_wrapper&Itemid=29