The easiest way, under Vista, is to go through the hard disk manager of this operating system. Open Windows Explorer. Right-click on My Computer and choose Manage from the context menu that appears to launch the tool called Computer Management.
In the left pane of this utility, click Storage, then Disk Management. Now you need to define the size of the partition allocated to Ubuntu. In the right pane, right click on the C: partition, choose Shrink Volume... and choose 8 GB or more as the amount of space to shrink. Don't forget to leave enough free space for Vista. A few gigabytes at the bare minimum. Close the Disk Management tool.
Under XP, you must use a partitioning tool such as Partition Suite from Acronis. The objective remains the same regardless of the software used: it is to create a disk space, unformatted, in order to install Ubuntu. Once in Partition Suite, click on the Create Partition link on the left side of the main Partition Suite window. An assistant will guide you through the rest of the operations. Check the Free space of existing partitions box, click Next, select your hard disk, and then designate the size of the partition where Ubuntu will be installed. Only format space allocated under a file system. Do not choose None as file system. At least 8 GB.
Whether you are XP or Vista, you must in both cases download the ISO image of Ubuntu 2 (nearly 8 MB) and burn it on a blank CD. From the Nero Burning Rom burning software, for example, select Open from the File menu, choose the Ubuntu ISO image, then click Burn.
Restart your PC from the Ubuntu install CD. An installation wizard launches and guides you through the steps. Choose Your country as the language of the operating system, then the entry Install Ubuntu. A menu appears, click Next. Validate the time zone selected by default, as well as the choice of the keyboard. Ubuntu's partitioning tool launches. Click the box next to Assisted Mode - Use Largest Disk Space. Set your Ubuntu username and password. Click Next twice, then click the Install button. At the end of 30 minutes, at the very least, the installation of this operating system is completed. A menu appears each time you start your PC: it allows you to choose which of Windows or Ubuntu you want to launch.
Audio Video Make Ubuntu 8 coexist with Windows XP or Vista - Install Ubuntu on a dedicated partition