It looks like it could be very useful. I'm happy to give input once you've added a few working features. For now the window looks fine, maybe add a min/max capability to it. Besides that I don't want to make any suggestions without knowing what you're planning on adding.
For instance I would suggest adding a drop down menu in the NUSD section, similar to the actual NUSD, which provides a list from which to select the IOS & version to download. Then adding to that, the ability (similar to ModMii) which allows the user an option to patch/not-patch that IOS automatically after it's downloaded.
Maybe a more comprehensive list of features you plan on implementing?