XF 1.2 Installing over vBulletin 4

Since I don't want to mess anything up before starting this, do I just go ahead and install XF into the same folder as Vb4, and then run the importer? Is it that simple?
Would I be better off creating a new temp folder, and installing the forum there to the new database, then doing the import from the old database?
XenForo installed successfully ;-)

How do I install a simple re-direct homepage in the root folder until I sort out a portal of some kind?