So now that workouts are included on the 500 I figure I should probably utilize them.
Garmin Training Center doesn't even touch power. I couldn't find anything on Garmin Connect. The only way I found to build workouts on the PC is through a plugin in Sports Tracks (which I otherwise don't use).
So I set my power zones in there, created a workout, and uploaded it to the garmin.
For starters, the intervals in which their is a target for power, on the Garmin it says there is no "target". When I try to edit the workout on the garmin to go to, say, zone 4, the zones are all off (they are very low, so I presume they are just the default zones).
I've tooled around a little in the Garmin to see if I can change the zones in there, but I haven't had any luck. The manual that came with the Garmin is no help (Because it doesn't exist...)
On my 705 you set the zones on the unit. If you program your workout using zones then presumably if your zones are different on the computer than on the unit you will get the unit zones during the workout. I don't like to use the zones because when it shows your power during the workout it shows it as what zone you are in rather than the power you are at. I don't find "zone 4.5" very useful for telling me what I am doing, personally. So I just program the workouts in on the unit directly with explicit power targets.