Its like when you have a cd and me an mp3 file (lossy), suppose i want to convert that file to lossless Flac i can't but you can cause you have the master (CD).
And most of all movies on TV are not truly HD, i mean when there is a remasterisation work behind (like a bluray) its pretty noticeable the HD but when its not you only see black bars.
My Computer
Computer type
PC/Desktop
Computer Manufacturer/Model Number
Custom Build
OS
Microsoft Windows 7 Ultimate 64 bits 7601 Multiprocessor Free Service Pack 1
But remember just because you have a higher resolution picture doesn't mean you have better picture.
( I haven't tried for I always believe in viewing video in its original resolution and aspect ratio.)
You may try and see whether it is acceptable to you. Individual perceptions vary. You may also find that some DVDs may look better in the upscaled resolution while some others may look worse.