Bill, when I purchased my D60 about one year ago, I got that one Canon BP-511 battery. Then I purchased one Lenmar substitute, which has a slightly higher mAH rating. Then I have been alternating those and using them a lot for this year. Finally, a couple of weeks ago, I sensed that maybe they weren't holding their charge quite as long as when they were new, so I bought another one from Green Batteries. For $30, it looks exactly like the Canon BP-511 and has the slightly higher capacity like the Lenmar. So far, I haven't shot more than twenty shots on the new one, so I can't say any more.
I use this rig for shooting weddings, so I can't have my batteries go belly-up in the middle of a ceremony.
I believe that you will get normal performance out of any of these as long as you charge them on the (intelligent) Canon charger. If you slide off there onto a dumb charger, then it can't be good for the battery, and it might be harmful unless you carefully monitor battery charging.
---Bob Gross---