I did a search but could not find this problem listed in that if you are using Firefox Portable on Windows 7 beta your bookmarks are stored by windows in the user folder even after you have removed the drive containing Firefox Portable from the pc.
IE: c:\user\yourname\AppData\Roaming\Mozilla\Firefox\Profiles\xxxxxxx.default.
just do a search for the rest.
Sorry if this has been posted elsewear if it has can a Mod please delete.
As it is a beta operating system, it's not yet supported. And no one should be running it for anything other than testing (running it as your real operating system would be an exceedingly bad idea), so it is not an issue at the moment.
Sometimes, the impossible can become possible, if you're awesome!
I do realise it is unsupported but it was more for information should anyone use Firefox Portable on a Win 7 pc as it will save their settings in Windows as I discovered when switching back to XP and a bookmark I had added while in Win 7 was gone but it was back when I next used Win 7 so I looked and found bookmarks saved in windows.