Install Linux Mint 14 as third OS after Windows 7 and Ubuntu Grub2

I would like to install Linux Mint 14 in a spare logical partition, but am afraid it would overwrite the existing Grub2 which boots to Ubuntu 10.04 and Windows 7.

How best to proceed?

Current setup:
Primary partitions:

• /dev/sda1 ext4 ubuntu10.04 /


• /dev/sda2 ntfs Windows 7


• /dev/sda3 reiserfs /home for ubuntu10.04 but will not be using it for Mint

Logical:

• /dev/sda5 ext4 this is where I want to put all of Mint14


• /dev/sda6 swap will use for both Ubuntu and Mint


• /dev/sda7 ntfs spare storage

I USB booted Linux Mint 14 and am at Install(as Superuser) screen and it shows /dev/sda (the whole disk) as the device for boot loader installation.

Is this the correct place for the bootloader? Will it find Ubuntu10.04 and Windows7?