Need help to connect external display to macbook pro so I can install Windows 7!

Hi! I have a huge problem... A few weeks ago, my macbook pro 2,4ghz fell into the ground and broke the display! The total cost to fix it is 700€... Almost 960dolars... I'm buyng a iMac 27" i5, but I would like to use this macbook pro connected to an external display..
So far, I've been able to connect it to an external display acting as primary display (it took me an hour to acess the system preferences, as I had to drag the system preferences from the broken macbook display to the external by trial and error)...

My only problem is that I installed bootcamp with a partition of 32gb in Fat32 to later instal Windows 7...
I was going to install windows in the day I broke the macbook pro display...
So now, when I want to log in to OSX, I have to press the Alt key on the mac to choose the OSX partition... I'm only able to do this by trial and error... I've managed to acess OSX by clicking the Alt key, and after a few seconds, I press right Arrow and down arrow and hit Enter...

Only after I do this procedure I'm able to use the external display...

Is there any way I can use the external monitor from the moment I press the power button on the macbook pro, so I can use it to install windows 7??!

I've tried to hit Command+F7, F7, but that doesn't work when I start up the computer.. Only after log in!

Thanks in advance for any tip!