If you look at the performance numbers you can see that the Sapphire X1300 XT OC has almost exactly the same performance as the X1650 Pro. Even though this means that the X1300 XT OC is just a very fast X1300 variant, it also means that there is not much of a reason to get the X1650 Pro instead. Basically the differences, other than the product name, are that you have a copper cooler, two DVI outputs and a temperature controlled fan. In my opinion the temperature controlled fan is the only interesting feature here that could be a factor when deciding between the X1300 XT OC and the X1650 Pro.
As card, the X1650 Pro is quite fast for the price range. Remember, not everybody is willing to spend 500 bucks or more for a video card, especially if you are only a casual gamer. As long as you stay below 1024x768, 1280x1024 in some games, you can even play at high details settings. In my opinion this card could be a good choice if you need a PCI-Express card today, but want to wait a bit before spending a lot of money to see how the whole DirectX 10 & Vista stuff develops.