XP Professional version will be available for auto download later on today. The Home version has been available for several days now but again only through auto update.
The SP2 "Hotfixes" you see at the moment in your control panel, add/remove is normal, I have 5 of them.
When SP2 is downloaded and installed, right click on your My Computer Icon and it will say XP SP2.
If you leave it set to auto download, it will download in one go if you wish or in parts as you go back on the internet. When the full download is complete it will auto install or manual install if that is the way you have it set.