do dvd/divx players play the movies i download from the net?

I'm thinking of buying a new dvd player that supports Divx.

But I was wondering does it support the videos i download from the net? or do i need to convert them to a certain resolution?

In another way, if i had a divx file with a resolution of 400x200 will it work on the player?

And what are the best divx players out there?

I'm thinking of buying a sony, but i would get something cheaper if it was the same quality..
thanx