Hey UncleSam,
The last link seems like your best bet so far, but as everyone is stating, do not just pick the one you think is best at this moment. If you have the funds to purchase the Lenovo ThinkCentre M58p, then it is a good choice. However if you are still saving money at this time, do not think it is the best one out there.
While saving money to purchase a PC, keep shopping, there will always be a better PC, no matter how hard you look. Just do not get disappointed when you do purchase one, and find a better PC immediately afterwards. It happens to me with anything I purchase, better deals come and go, but they always seem to go on sale after you already purchased the item. Just saying...
Edit: You also did not mention if you are needing a keyboard, monitor, and a mouse. Some PC's do not come with them and allow the consumer to purchase them on their own. Sometimes there are good package deals, and sometimes the package deals are a rip off compared to purchasing separately. For the money as I mentioned, that link is a good deal, but for a hundred dollars more, there are much better PC's. Find a limit to what you want to spend, and maybe we can even help you shop.