for chrome, go to C:\Users\username\AppData\Local\Google\Chrome\User Data\Default\bookmarks.bak
copy that to the same location in the new user account (backing up any current bookmarks file that may have been created) and delete the .bak from the file name. your bookmarks will show back up.
for firefox, I believe its C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles\someprofilename.default\bookmarkbackups
I never use firefox so im not entirely sure if copying those will do the trick. I did however copy the entire Profiles folder for a buddy and copied it into the corresponding folder on the new account and everything came back just fine. settings, bookmarks, etc.
again, backup the files/folders before you do this in the off chance that something goes wrong.