Gunny, as a starting base that's not too shabby at all. I just ran that on selected meetings Jan 1 - May 31 2011, looking at the top 2 only:

Races: 4288
Wins: 1593 (37.2%)
Bets: 8575
Return: 7795.30
Loss: 9.1%

2 horses per race, every race & less than 10% loss on NSW TAB.