k so i just got back from the store, and i was forced to get a MX310, because they were out of stock, but its still a good mouse, not for gaming or anything, its not for me anyways, just my moms for work.
its actually pretty good, ergonomically, but wat i dont like is that you no the back and forward buttons, the forward button on the right side of the mouse is place pretty far down your pinky so you have to move your pinky down a bit to reach it, thats the only downside. otherwise its excellent, but i would've really wanted to get the mx510. oh well. shiz happens.