[geoschmo]

If there was a planet that could support human life in our system we could colonize it. If nothing there was edible, at least we'd be able to transplant our own flora there. If it would support human life I can't think of any reason it wouldn't support other earth species. So you might be talking about a period of terraforming, but it would probably only be a few years before a small colony there could be self-sufficent. Perhaps only a single growing season.