Think I've done a dumb thing.... tried to install Windows 7 on my Apple iMac by inserting the installation disc with desktop showing. Thinking the install process would guide me through. Windows 7 would not install because of "incompatible format on the available disk drive partitioned space". When I quit the install it justs restarts and tries to reinstall. Cannot eject the disks as cannot get back to desktop, no response to the eject key on the keyboard, tried turning off the power, tried control/alt/delete and got another Windows screen. Any suggestions to get the Windows DVD out?
Turn the iMac off (if necessary by forcing it to shut down, by holding the power key down). When you turn it on, immediately hold down the mouse button and keep holding it down until the disk gets ejected. For the benefit of anyone reading this question who has an Apple Laptop, the equivalent procedure on these is to restart the machine holding down the eject key. However, as Kirk pointed out in the comment below, you can also hold down the trackpad mouse button to achieve the same effect.