Possibly when you ran the commands, or installed Linux, you overwrote the boot sequence needed to get to the required menu?
Do you have any other DVD/CDs from Gateway, or have you checked to see if you could get some?
The 1 MB partition you have at the front bothers me a little since I have seen that after some dual boot installs. I will assume it did not come that way.
If you open an administrative command prompt in Win 7 and type bcdedit, take a snipping tool picture of that and attach. You did say Win 7 is booting normally...
Operating System Win 7 x64
Computer Type Homebuilt
OS Service Pack 2
DirectX Version 11
CPU Type and Speed i7 3770K
Motherboard Chipset Asus P8Z77-V Pro
System Memory Type 16 GB Kingston
Video Card Type and Speed Nvidia GTX 680 (2)
Computer Monitor LG 27" (3)
Hard Drive Kingston 240 SSD
Optical Drives LG WH12LS30 Blu-
Modem-Router Type Linksys E3000
Network Adapter Intel Gigabit
Anti-virus Software MSE
Computer Skill Level Average Ability
Windows Experience Index 7.7