This is a low power Net Book with a very low powered CPU an dis only capable of running the most basic version of 7.
The version that is so basic that it is not available in your country but only third world countries.
Second issue is that the 7 Install Disc is a DVD not a CD so you need a External DVD Drive to load this OS.
But if you insist on loading this I wouldn't recommend you activating it as you will be wasting a Windows 7 Ultimate License as you'll find that this system is unusable and by activating that License you will be tieing it to this Hardware forever more.
Here you need to make a Slipstreamed Install Disc and include the Acer Aspire 1 SATA Drivers for Vista as there are no Windows 7 ones. To do this you'll need vLite available free here
http://www.vlite.net/download.html
Just make sure to read the Help Files available here
http://www.vlite.net/help/
These Net Books do not have enough processing power to even run XP Professional well if in a usable manner and come with the Home Version of XP for a very good reason. It has the lowest Windows Resource Foot Print available. By loading even the Home Version of 7 will overload this system but the Ultimate version is not only a waste of money but a waste of perfectly good hardware for what it was designed for . The Net Book will be so slow that it will effectively be unusable.
If you are unhappy with the performance of XP on this hardware you will be devastated by the performance of 7 and if you want better performance try the Ubuntu Net Book Remix available free here
http://www.ubuntu.com/getubuntu/download-netbook
Col