New to HTPC need suggestions

[blbeta]

I am turning a PC into the hub for my Home theater. I know computers and hardware well. I do not know anything really about DVR hardware or software for PCs.

Here is what I have-

PC:
Amd XP 3700+
2gb ram
250+ gb hdd
Nvidia 6600gt
Gigabyte GA-K8N Pro SLI
Win XP Pro

Cable:
Comcast
Motorola DCT 6412 III

Tuner:
Marantz SR4500

TV:
Sony VLP HS51
Input A: VGA connection running at 1280x720


Here is what I want to accomplish-
-Media Server
-Dual tuner DVR (HD and 5.1 audio if possible, similar to the STB from Comcast)
-Ability to record HD channels as well as premium channels
-Adaptability to Satellite, FiOS or any other if I decide to change providers
-1:1 quality for my Dvds/Cds, possibly Blu-ray down the line, stored on the server and ready for use
-Ability to access everything that stored by other machines on my network. Meaning being able to watch/listen to everything on the server including shows from DVR


Final Question-
What hardware/software would you recommend I look at?
Where else should I look on the net to educate myself?

I currently just use VLC player to run my Dvds and everything works and looks great. I am now just wanting to add functionality to it.

Thanks in advance.