If you create a usb key using the guide on a 4gb flash drive you won't have much of an option there due to seeing less then 750mb left! USB Windows 7 Installation Key Drive - Create
The 8gb you have there will have the space available while creating a few new folders rather then seeing loose files copied over to it would prevent any problems if you need to install 7 again with it for some reason.
The small 4gb and 2gb flash drives here were simply set aside for the 32bit and 64bit 7 keys as well as the smaller 2gb used for GParted. The larger 16gb and 32gb models can act as data rescue tools since those are just a bit too large for usb keys there. And second partitions on flash drives to store files won't work there since Windows will only see the first on any flash drive.