I have owned an xbox for a large number of years now. I did have the normal xbox 360, but after a number of pre-owned stuff I bought from a certain UK game retailer broke, I complained and got my hands on a free 4GB xbox, as well as a number of games. I have survived for around a year on the 4GBs, however I felt that now was the time to upgrade, with downloadable games becoming more and more frequent. Usually, when buying DLC, I would have to delete a map pack, for example, to accommodate for the latest one. I don't think that is very good.
So onto the product. Even the most techno phobic person could install this. That certainly isn't me, and I had no trouble, you just turn the xbox upside down (Make sure it isn't on) and press the small catch. You then just slot it in. You can then copy over all your game saves/files and re-download any DLC/Other purchased items.
320GB Is masses of space, although in reality it is only about 302GB. That is enough to fully install to the hard drive 50 average games (6GB), allowing them to run more smoothly, make the xbox whisper quiet, reduce heat, and sometimes improve graphics.
Also, at the time of writing, this is exactly the same price (£64.99) than the 250GB one, which is great, for 70GB extra storage. It may also be worth noting that this does come with a free Lego Star Wars game, available to download of the XBL marketplace with a redeemable code. Not that I will ever play it, but it is a nice touch.