Let's find your Bookmarks file and copy it.
But here's a difficulty. I'm using Windows 7 and you're using Windows XP, so there are differences.
Can you use Windows Explorer? It is the same window that you use when you open My Computer, or My Documents, My Pictures, My Music, and so on. Windows Explorer can be found in Start > All programs > Accessories. if you open that it should have two panes, left and right. Anything you highlight in the left pane will display in the right pane.
First step, Unhide files and folders. In Explorer, go to Tools > Folder Options, then click the View tab. If there is a tick for "Don't show hidden files, folders or drives", tick instead the one below, "Show hidden files, folders and drives". Click Apply then OK.
I can't remember what is displayed in the left pane when you first open Explorer, but whatever it is, will have a small + sign next to it. Click that, and keep clicking until you see (C: ) which is your hard drive. Click the + besides the C, and at the same time, highlight the C to list the folders in the right pane.
In the left pane, look for "Documents and Settings", then highlight and click the + besides that. Then start drilling down the sub folders under your own XP account name.
I think it will be something like;
C://documents and settings / {YourUsername} / application data / mozilla / firefox / profiles / {RandomCharacters}/
Highlight the random characters folder and the list of files it contains will display in the right hand pane.
You are looking for two files, "bookmarks.html" and "places.sqlite".
Copy those to some safe temporary place, like your Desktop. For full safety, copy them somewhere else as well,eg a flash drive, external drive or CD.
The bookmarks.html is the one used for Importing and Exporting. The places.sqlite is is where the actual Firefox bookmarks are stored, and we are copying that for double safety reasons, in case bookmarks.html fails for some reason.
Now that you have your bookmarks saved, you can go ahead and uninstall Firefox, reboot the computer. I would then manually delete all folders relating to Firefox, both in the Documents and Settings folders, and in Program files. Do not delete any Mozilla folders if you use Thunderbird, the email software. If you use something else for email then go ahead and delete all references to Mozilla.
For good measure, reboot again.
To reinstall Firefox again, there is no need to disable any security programs.
When Firefox is reinstalled, you can Import the bookmarks file from Firefox's Bookmarks menu.
Good luck.
Mark