So I want to build an HTPC DVR...

1.) No idea, but WMC seems to be the go to solution for HTPCs.

2.) Depends. Is this strictly an HTPC (no gaming)? How much do you have to spend? I tend to recommend an i3 and H55 board with integrated graphics (enhanced onboard graphics) for HTPCs.

3.) Besides getting true HD? There's also bitstreaming, or delivering both audio and video. Regardless, it's pretty much the standard, so it's advisable to use HDMI.

4.) I would go with separate cards. Or with the i3, a single card (the TV tuner).

5.) Not really. This is kind of a niche market.

Here's about what I'd look at. I'm leaving out the TV tuner, because I simply don't know enough about them to recommend one. Also, keep in mind that Sandy Bridge (Intel's next CPUs) is due out in a week or so. They're supposed to be like the second coming....

I have a question that will impact the optical choice. What exactly do you mean by "play BluRay files"? Do you actually want the disk to be able to be played on the PC, or do you want it to do 1080p streaming?

CPU/Mobo: i3-540 and Gigabyte GA-H55M-USB3 $193 after rebate
RAM: Kingston ValueRAM 2x1 GB DDR3 1066 $26
HDD: Samsung Spinpoint F3 1 TB $70
Case: Pick out one you like. Make sure it's either ATX or microATX
PSU: If it's a media center case, it's likely to have a PSU already in it. Use that. If it doesn't, Antec Earthwatts 380W $30 after rebate
Optical: Assuming you don't want a BluRay player, pick up literally the cheapest SATA DVD burner you can find. If you do want a BluRay player/burner, pick up the cheapest one you can find (either with or without software, whichever you want). The DVD burner will be under $20, the BR player will be around $50, a BR burner will be around $100.

Total: $419, without case, assuming BR burner. $339 without case, assuming DVD burner.

no gaming needed. i use my desktop for that.

Playing bluray files... I run a software media server on my PC, and can stream .mkv files to the ps3... but like I said, not a necessity.

I like your numbers. Not sure if i want to wait for intels next cpu... im sure it will be overpriced anyway.

Thanks for your help tho, I may copy ur system!

Anybody give any input on tuner cards?

You don't need anything specialized (outside of software) to stream files. It's just like any other media being played back.

I'd wait for Sandy Bridge. Right now, it looks like the new i5s/i7s will come into the market at roughly the current prices, which will drive prices down significantly. The new chips are also supposed to see a 20-30% bump in performance, according to anandtech's preview.