If you need to install a computer/server fast, use a USB drive. It's very easy and if the USB drive is large enough you can also add drivers/programs.

This nice utility does the work for you if you want to install Windows Vista/7/2008. Just feed it with a USB drive minimum 4 Gb and the ISO file: http://www.askvg.com/a-bootable-usb-utility-to-create-bootable-usb-drive-to-install-windows-vista-server-2008-and-7/.

If you want to install VMWare ESX v4.0 from USB, try this utility: http://unetbootin.sourceforge.net/ I think that this can also be used for the different versions of Windows, but I haven't tried it yet. To install VMWare ESX when you have booted from the USB drive, press TAB in the first menu, when you're presented with the different install options. This brings up the standard line of install options to pass into the kernel. Add ASKMEDIA to the end of the line and press ENTER to start the installation.

Remember to choose to boot from USB (This is done in the BIOS).