Setting up extended display on Mac Leopard

I have been wanting to hook-up the 20" Dell LCD at work to the Macbook as extended display. I explored this in Leopard and found that setting the Dell as extended desktop was easy - use the "Displays" program in the "Systems preferences" and simply click on the "detect display" button. Mirroring (you see the same desktop on both the laptop and the Dell) was also easy - simply click on the mirror option after the extended display has been detected. A problem with the mirror option, however, is that the desktop on the Dell does not occupy the whole screen; adjusting the resolution does not fix this. So, the mirror option is not ideal for people who would like to fully utilize the extended display.

My aim was to use the Dell screen as the main desktop and put the Macbook to sleep. A solution to this would be to turn the Dell as the main desktop and the Macbook as the extended desktop. Setting the Dell as the main desktop would allow me to see both the dock and the top bar. After doing some Google search, I learned that I could turn the Dell into the main desktop if i placed it directly below the Macbook under the arrangements tab in the "Displays" program.

The next problem to solve was to keep the Dell desktop alive when the Macbook lid was closed to put it to sleep. Closing the lid affected both desktops (both went to sleep). After doing some more Google search, I learned that I can wake up the desktop on the Dell by inserting an external USB mouse and/or keyboard to the Macbook while it is sleeping with the lid closed (if the mouse/keyboard are already inserted, remove them and insert again). I was a happy man when my Dell woke up upon inserting the external mouse and keyboard. It is so much better to work on a bigger screen!