virtualbox.org

I have installed the GA (Guest Additions) and now I'd like to unmount the virtual CD-ROM (the optical disk device) . It it allowed or should I leave it there and "connect" another virtual optical disk device ?
In case it's needed , I am using WinXP installed on Win7 .

Yes, you can eject the CD media, just as you would after installing any other software from CD.

In fact it is recommended that you ALWAYS remember to unmount the GAs media, because that ISO gets overwritten on every VBox update, and externally modifying media that is currently mounted... can lead to problems.