HDMI Question???

So I got an Xbox 360 Elite and I wanted to use the HDMI Cables but I don't have the tv with those inputs and well I wanted to get the best resolution. Now I have a pretty nice LCD monitor that I wanted to use as a tv and well I bough a tuner but when I use the components connections it's not the best resolution, it kinda looks like crap. I have an ATI All in One Wonder HD TV Tuner and that is what I am using. So to make a long story short is there a HDMI PCI Card for the computer?? I looked everywhere and well I am so confused and really don't get it. I am new to this, so any help with be appreciated. I am willing to spend about 100 to 200 bucks if there is something out there but of course the cheaper the better, thank you. Also if you think I should use another TV Tuner that will be appreciated to, that is if you think the one I have is a piece of crap. Thank You!!!!