I'm trying to find an hdtv card that will not lag with my HD cable box or my 360 while hooked up to my htpc. I am running a p4 1.5ghz w/ 256mb pc800 and an ati radeon x800 video card. What would my best option be for my setup?

I'm not sure what you are asking, but an HD tuner card will only tune Over the air channels or unencrypted canble channels if it has a QAM tuner.

They do not have HD inputs.
Some cards have an analog side but those will only input 720x480.

My cable box has conponent in. HD cards do have one hd input over the coaxial connection. The way you use the input is by tuning to the cable box's output channel.

What I'm asking is very simple; I want to find the card that has a low draw on my computer's resources. My goal is no lag for my 360.

That isnt really how it works, the HD cable box can't output HD over coax. It will only output over component, HDMI, DVI, or VGA. Also, more than likely there is some delay in the HD card writing to the computer then output to the screen making it almost impossible to play games. The best option is a transcoder or use a LCD tv with hd capabilities (like my magnavox, it can downscale 720p to the 1024x768 screen.)

No worries! I went with an lcd replacement! Instead of my 4:3 dell 1703fpb that uses svga only, I'm running a LG FLATRON L173WT with dvi-i and component input! Best $100 I ever spent! Now to find a component splitter for my xb and hd cable...

I've got to say, the L173wt is a very easy strip, and if you're okay with your board being on the outside of your enclosure, works great! Not to mention best of both worlds with dvi and component inputs!!! Thanks guys!

I will never understand going cheap on the lcd (PC Monitor) then spending $100-200 on a box to get the right connections. The TV is the best way to go IMO.

I've done both, and I definately agree with matzner. Spend the extra and get a monitor with the HD inputs right on it. Transcoders work, but they get old fast when you have to switch them around. I don't know if there are any HDTV cards that you could play your Xbox through. I have the Kworld PCI 115 HDtv card and there is way too long of a lag for video games to be playable, I find using a remote frustrating at times. This thing does work great as a PVR and tuner, but something direct is needed for gaming.