Whichever driver you decide to purchase, the length is going to be a standard which is going to be 45"-45.5". Many golfers prefer a driver that is 44.5"-45.5" though. The shorter the shaft, the easier the club is to control and the more fairways you will hit with a predictable ball flight (less spraying). The downfall to a shorter shaft is a distance loss, but typical losses from 45.5" to 44.5" are 10-20 yards depending on the person. Again, if you get a driver that is any longer, you will most likely not be able to control it and you will be making the driving part of your game much more difficult than necessary.
Do you know your swing speed with the driver yet? If not, you definitely need to have an idea before you make an 'off the shelf' purchase. The shaft and shaft flex in the driver you purchase is going to be one of the most important factors in determining your control and ball flight.
The two links that you provided are different as well. One is for a left-handed club (Stiff flex) and the other is for a right-handed club (Senior flex).
Also, keep in mind that you can pick up a used driver at your local golf shop (such as Golfsmith or Golf Galaxy) for right around the price you're looking for. Most of these drivers will also have modern technology in terms of interchangeable shaft and Open/Neutral/Closed face settings.