You should be able to upgrade the CPU since it is not soldered into the motherboard. The hard drive can be upgraded as well as RAM, however, that is the extent of it.
The graphics cannot be upgraded because they are soldered into the motherboard. I suppose if you know of someone who knows what they are doing and you can get a hold GT 540m it is possible to solder it in. However, I am not sure if the BIOS would recognized even if it is soldered in properly. There may not even be a port / pin holds to solder in the graphics chip to begin with in the motherboard if yours did not initially have a discrete graphics chip.