Do video cards make a noticeable difference in movie watching?

Im buying a dell (http://configure.us.dell.com/dellstore/config.aspx?c=us&cs=19&l=en&oc=DXPS400F1E&s=dhs) and it comes with a video card ATI Radeon X300 SE HyperMemory 128mb, i was wondering if there is any noticeable difference if i only use this to watch movies. Because Right now my computer is running a Radeon 9200SE 128mb and i cant see any difference compared to anyone else. even a 300$ video card. Is it just me? does this really affect movie watching?. And the same about Audio cards. I have a Sound blaster 5.1 and dont know if its worth upgrading to a THX sound card. would there be noticable difference?