Should I get an HDTV?  

I'm looking into getting an HDTV to replace my old TV.But
I'm not sure if I'm better off with an HDTV. I use basic
standard def cable and am hesitant to get the digital HD
package because I use a Home Theatre PC to watch cable.. I
use BeyondTV, and have a Hauppauge WinTV-PVR-500 (dual tuner
card), and a PNY VCG62128APB GeForce 6200 video card which has a DVI output.So I would have standard def going through the computer and have it come out the DVI to the HDTV.I use the computer for watching TV, videos, and DVDs so if the card would up convert and look good on a HDTV I would be all set,but if the DVI output won't give a great picture then there's no real reason to get a HDTV.
I live in Lincoln, NE and there are some HD channels over the air so I would get an over the air tuner so I could watch those in HD. I did some googling on the video card and didn't see much talk about how the card outputs to a HDTV.