Windows will try it's best to nuke grub if you install it after Ubuntu.
Install Ubuntu after Windows
https://help.ubuntu.com/community/WindowsDualBoot
A Windows OS should be installed first, because its bootloader is very particular and the installer tends to overwrite the entire hard drive, wiping out any data stored on it. If Windows isn't already installed, install it first. If you are able to partition the drive prior to installing Windows, leave space for Ubuntu during the initial partitioning process. Then you won't have to resize your NTFS partition to make room for Ubuntu later, saving a bit of time.
When a Windows installation already occupies the entire hard drive, its partition needs to be shrunk, creating free space for the Ubuntu partition. You can do this during the Ubuntu installation procedure, or you can see How to Resize Windows Partitions for other options.
If you have resized a Windows 7 or Vista partition and cannot boot up Windows, you can use the instructions from WindowsRecovery to fix it.
