RealPlayer & Windows Media Player resolution

Hello all,

After installing Vista and playing the video clips that I downloaded when I
was using Windows XP, the video resolution seems lower (video images more
'blockky').

My monitor was the same in both operating systems.

When I played this videos, I did get a message that says somehting like
"format being converted to Vista Basic colour scheme' (Not exact wording).
Does this effect the video resolution?

Thanx in advance.

L & L