The third partition is for the root file system. A new installation of Mint 10 (and Ubuntu 10.10) takes up less than 3 GB of disk space. So anything more than that should be good for this partition. Keep in mind that because we are not using an LVM-based partitioning scheme, resizing these partitions will not be easy, if at all, For this installation, I allocated more than twice the required size to this partition. For file system type, the default, ext4, is good. If you want to install the system on a btrfs file system, the instructions for Mint 10 and Ubuntu 10.10 are available here and here. The mount point should be /. Note: If you choose btrfs for file system type, this should be the last partition.

Click OK when you are satisfied with your choices.
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The last partition will be for /home. The available space should b allocated to this partition. The default file system is ext4, and the mount poing should be /home. OK.
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All the Linux partitions have been created, and the Windows partitions are untouched. Before clicking Install Now, there is one more task, and it is very important. Where do you want to install GRUB, the boot loader? By default, the installer will install GRUB in the MBR (Master Boot Record) of /dev/sda, the primary disk where Windows is installed. That will make GRUB be responsible for dual-booting. The problem with that, according to some reports, is that the Windows installer tends to overwrite aspects of GRUB the next time Windows is updated or upgraded. The best option then is to install GRUB where Windows will not see it and, therefore, be unable to mess with it.
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The recommended location to install GRUB in this type of configuration is in the MBR of the second disk (/dev/sdb), where we are going to install Mint. The other recommended location is in the boot partition of /dev/sdb, which in this case is /dev/sdb1. Whether you choose /dev/sdb or /dev/sdb1, you will need to edit the Windows Boot Manager and add an entry for Mint (or Ubuntu) after installation has completed. Click Install Now to continue with the installation.
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The installation should take about 15 minutes. When you reboot, and assuming you installed GRUB in the MBR or boot partition of the second disk, the computer will reboot into Windows 7. Now, you will have to edit the Windows Boot Manager and add an entry for Mint (or Ubuntu).

To make editing the Windows Boot Manager a bit easier, I recommend that you install EasyBCD, a free application from NeoSmart Technologies which you may download from here. After installing EasyBCD, start it and follow the steps given below to use it.

This is EasyBCD’s interface. It shows that the Windows 7 boot menu has just one entry. We need to edit it to add to entry for Mint (or Ubuntu). Click on the Add New Entry tab.
ebcd