Putty can emulate the Xterm copy/paste style. It is not the default but it can easily activated
In Emacs it is a bit more complicated. The following definitions are required in the .emacs file:
(setq select-active-regions nil) (setq mouse-drag-copy-region t) (global-set-key [mouse-2] 'mouse-yank-at-click)
In Firefox the paste style can be activated in about:config. Search for "middle" and set middlemouse.paste to true.
In order to copy the selected text to the clipboard it is necessary to install an extension. AutoCopy 2 does the job.