Ah you already have a lense! The EF28-90 should work with the DR, just multiply by 1.6
It will work as a 45mm-144mm.
The kit 18-55 that can come with the DR works as a 28.8mm to 88mm in 35mm equivelance. The 18-55 is getting good reviews from owners so it is not a bad option if you like wider angle images.