WinDVD-bad quality picture with 7800GTX and high range LCD!?

Okay first of all ill admit that im a newcomer to playing DVDs on my PC so maybe im expecting too much. Anyway i decided to use the softtware that came with my Asus motherboard, WinDVD Suite. I was expecting a really nice quality picture cause of my nvidia geforce 7800GTX graphics card and my high range LG Flatron l1980q 19' LCD monitor but was very dissapointed with it. I mean the picture quality is not very sharp at all and is slightly blurry and although it is watchable i just cant stand the fact that my 10yr old CRT Sony TV downstairs is 3 times better in quality!! I will point out the fact that i have my nvidia display settings at default (aa off etc) so would that make a difference? Either there is an explanation for this or my PC is just not working... So could someone explain whats happening or how to solve it. thanks.