HTPC Advice needed for watching HDTV



I am planning to build a gaming PC/HTPC in the early to middle part of next year for around $2,000. I currently use a Time Warner HD DVR cablebox and plan to continue using it to watch and record shows when I build the PC. My question has to do with where I should connect my cablebox. Am I better off connecting the cablebox via HDMI directly to the 1080p HD television and routing the audio to my sound card or is there an internal TV Tuner card that supports 1080p or 1080i? I have not found any tuner cards that have HDMI input. If the TV tuner card is the better option, which brands are reliable and how do I send an HD signal to the card? I am not planning to do video editing, I just want to watch my HDTV shows but I am uncertain which option I should choose. Thanks.
I have Time Warner Cable, and purchased the SiliconDust HDHomerun Prime:

It provides 3 networked tuners and with the use of a Cable Card and SDV Converter (call it a "TiVo Converter"), I get all the channels my cable boxes had EXCEPT on demand. If you want on demand, you must use their cable boxes.

With Windows Media Center, I can watch and/or record up to 3 programs on any computer and XBox 360 in my home. HD Channels are in 1080i (max resolution from Time Warner Cable), and my main TV in the family room is connected directly to my HTPC.

The good side: Saved $60 per month on the cable bill, I have 3 tuners to record from (instead of 2 from TWC), and all my devices can stream live and/or recorded TV. It beats the overall performance of the "whole home DVR" functionality of TWC.

The bad side: No on demand TV (I never purchase on demand).

Ceton also makes internal cards and USB 4-tuner devices:

I did not purchase the Ceton products for one reason - the tuners must be dedicated to a PC (you can share them, but they have to be assigned to a PC), where the HDHomerun Prime is networked, and any device can request the tuner, and when finished, releases it back to be used by another device.

When building the PC, any of the core i-3, i-5 or i-7 processors do a good job, the integrated graphics is enough for HD video. For gaming, depending upon the games you play, you may want to look at a higher performance video card.

Start with 4GB RAM, and add 2GB of RAM for each WMC extender you used. With the price of RAM today - I would install 8GB or 16GB.

I would also suggest using multiple hard drives to store recording - 1 for "buffering" (this allows you to pause, rewind, fast forward for up to 2 hours) - 1 for recorded TV (dedicated), and 1 for your operating system. Just makes things run smoother...especially if you typically record multiple programs while watching TV.

Also - it is recommended to use Cat 5e/Cat 6 cabling and use wired connections to the HDHomerun Prime and all PC's/Extenders that will be used. I have 1 XBox wireless, but there are often times where the signal can effect performance on HD the wired connections are best. Make sure to get a 1GB Router or Switch to support the network traffic.