Well, FIFA 2001 definitely looks better...I think you wil also have noticed that the camera-position s altered, I myself had to get used to that, but anyway...I like the option in FIFA 2000 that allows you to play with classis teams.
I have the illegal version of the game, so I didn't have to buy it
But if you want more realism, the option to create your own league/tournament, updated teams, some of them with this year's shirt sponsors as well, you should go for it... just don't expect the gameplay has improved.