can I run two versions of safari side by side On a freshly intalled computer rather then importing my old safari bookmarks (ea wih migration assistant) I want to start anew with no bookmarks. However, from time to time I would like to browse through my old bookmarks (on the 'old safari') to selectively drag a few bookmarks over to the 'new' safari.
Both new and old safari's are in fact the same version.(what if the old was leopard and the new was snow leopard, does the old run inside SL?)

An extension to switch bookmark libraries wouldn't solve this, as I need both bookmark lists open in a window to drag and drop bookmarks from one to another.

So I guess I could use http://michelf.com/projects/multi-safari/ but feel this is more then I need: I wonder if I can do this with both safari's using the same webkit version of the OS (just like camino uses the same webkit as safari and can be open at the same time)

Also would it be possible to run the old safari from an external disk, so without it being located in the local applications directory?
Unfortunately, Safari does not support multiple user profiles.

Even if you create a copy of Safari.app and execute it separately, both of them will load the same user profile which lies in your Library.

But, if your only requirement is the selective bookmark transfer, then you may export your bookmarks from your old machine as a html page, open that page in your new Safari, and selectively add the bookmarks as you wish.

In order to export the bookmarks, you just need to go to File > Export Bookmarks.. and then just open the resulting file from your new Safari.