The ABS version has two clear anodized (silver) round inserts/bolts/plugs clearly visible on the outside of the front calipers instead of anodized blue for the non-ABS version.
Here's an example of the non-ABS in pics from the classifieds section: '05 non-ABS for sale -- see the blue aluminum caliper inserts/bolts/plugs on the front calipers. If it were ABS, those would be silver.
And Iggy's not only faster than I am, but correct about the "ABS" designation in small letters on the sides of the front fender.
Ride the bike at a brisk pace accross a wet lawn. Quickly apply both brakes as hard as you physicly can. If you smoothly come to a stop, the bike has ABS. If you end up eating turf it don't.