Hi, I just installed parallels on my air because I need to use some windows application. However, when I removed my external CD drive, it showed me a message saying that the CD is missing and cannot run windows. Do I need to use my windows installation CD everytime I run parallels? Also, does anyone know if the programs on windows would take up a lot of space on my mac (since i installed it on a virtual machine instead of on the hard drive like what happens with boot camp)? Thanks!