There unfortunately isn't a whole lot you can to with only one display output on the entire computer. You could buy a VGA adapter as mentioned before and try using the tablet as your only monitor, or you could get an adapter and a VGA splitter which will show the same image on both your monitors. This works best if both monitors have matching resolutions though, or else the higher resolution display (likely your tablet) will be forced down the the resolution of the lower resolution display. If these methods won't work for you, you are pretty much stuck with your laptop. Since storage is an issue, you could transfer a bunch of stuff off the laptop and store it on the desktop instead, but this may not be worth it if the laptop is unbearably slow compared to the desktop.