This is just a note on what I've tried and worked.
Operating System: Win 7 X64 Professional (pre-installed), wanted to install Linux Mint 16 Cinnamon x64
I followed the installation guide here:
hence I didn't choose "alongside Windows 7" option during installation,
after installation it seemed didn't install grub2 at all, so I can only boot to Windows.
Then I used live-CD (actually live-usb) to boot to Linux Mint again, I followed this guide to re-install grub2
It worked, but then the computer only boots to Linux Mint, can't go to Windows anymore.
I guess at this point you can just edit grub2 config if you know how to do it, but I don't,
so I grab a tool called "Grub Customizer":
it's a GUI tool to configure grub2.
Unfortunately, it cannot be found under package manager or synaptic, so you have to compile it (just follow the README)
After that I executed it, and turn on "show menu" option under "General setting" tab, click save, problem solved.
Next time: try just use Grub Customizer, or even better, use a VM inside Linux for Windows 7 (If I have another product-key available....)