The i5 with the radeon is much better. AMD vs Nvidia on the very low end cards, radeon does very well, usually drawing less power and performing the same or better. Nvidia does quite well on high end cards however. You'll see better performance all around on the i5.
Edit: i said corrected, i didn't see the post above, looks like you'll see a little better performance on a 525 but i'm not sure it would be by much.