If you see Ok button not becoming active even after filling data on "Android Virtual Device Manager" then it may be the case of "CPU/ABI" is not having system image for your Target SDK. It may be telling you so there!
To make it work, go to Eclipse's Window -> Android SDK Manager and install system image (ARM/Intel or MIPS) according to your target Device.
Even after installing ARM EABI, I could not create Android Virtual Device (AVD) with the desired Target API Level as the CPU/ABI was not coming in AVD creation. Then I restarted the Eclipse and it got the CPU/ABI value and then OK button has grayed out.
If needed then get More info on AVD problem here.