I wanted to create a brief post to note the dimensions of the logos used for Windows 8 Store applications for future reference:
So to submit an application to the Windows 8 Store only four logos (in bold) are actually required.
The 80% size is used for low DPI display modes while the 140% and 180% sizes cater to higher DPI / resolution displays.
So while you can get away with the recommended minimum you will not be able to guarantee that your icons will look good across the whole range of displays where Windows 8 will be deployed.
I recommend looking at the following msdn resources for anyone interested in further reading: