You can go the route listed above, of course. This still will not fix the problem of setting adw to default-home, if you have ever switched back, since the xperia crashes when you hit Set to default"
The easiest way to set ADW to default is go to settings > Applications > Sony Ericsson Home. At the bottom, click remove defaults and hit your Home key. This will cause the default chooser to open and you can choose AWP. This is far more space efficient than downloading another program. As a Sony Playstation fan, the experia never seems to have enough space, even with a 16 GiB card.