I am looking at a flight from Milwaukee to St. Thomas. Delta offers a flight from Milw. that lands in Atlanta at 8:55am and the connection flight leaves Atlanta at 10:00am. Thats a 1:05 layover. Is this a good idea? Id REALLY like to make it happen, but being inexperienced at flying, Im hesitant.

In normal circumstances this is enough time. I've done connections in Atlanta with about the same amount of time, and I've had no troubles. The airport is gigantic, and you might have to do some fast walking, but the transport system is good. To me, the Atlanta airport doesn't feel any more spread out than DFW, and I routinely have connections of less than an hour there.

You don't mention when you're flying, however, and that can be an issue. If your flight were delayed, you very well might not make the connection. Is there a later flight to St. Thomas from Atlanta that day?

I would be traveling in June.
There is a different set of Delta flights, but the layover between them is also 1:05. The Delta flights with 1:05 layover is at a really good price and I'd get to St. Thomas at a good time of day, that's why Id like to make it happen. But I dont want to put myself in a nad position either.
It seems Delta connects in Atlanta and US Airways connects in Charlotte.

I think you should be fine. I never worry about connections (on the same airline and traveling within the US or US to outside the US) with at least an hour, as that is considered a standard connection flight. You can never tell when a flight is going to be delayed for mechanical or other reasons, but I think you are putting yourself in the best possible position by getting the earliest flight of the day to ATL.

i looked and neither of your flights should be a problem, as you won't need to change terminals. in atlanta you may need to walk quickly to new gate, or it may be the next gate over. 50 mins in charlotte is plenty of time to get to new gate. bottom line is they don't book you for changes you can't make as it just causes them problems.
early flights are least likely to be delayed and in june you should have no weather relataed problems.
atl is the delta hub so most every plane they fly goes through there. usair hub is charlotte so same deal.
i'd book the early flight.