its sensor performance, the 11point AF system, better ergonomics etc.blueren said:Why that order? What makes the nikon better than 500D?
now if i may add to this debate,

go for the D90 over the D5000, now that i'm looking at lens options... one of the first that you would look for, a prime..
the AF 50mm prime (which wont AF on the d5000) costs under 6k
the AF-S 35mm prime (which will AF on the d5000) costs 12k
NOTE :: all of these will AF on the d90
so thats a huge saving, on 1 lens alone... when you get the d90 over the d5000