is it possible to upgrade the memory of the video card of my n150 netbook?
If you are asking about upgrading the memory of the GPU within your n150 netbook, I would have to safely answer no. But, if there is a will there will always be a way.
The CPU and GPU are usually hardwired altogether on the mainboard so your best bet may be upgrading the ram and possibly replacing the hdd with an ssd but you won't gain much. I'd say your ROI will be nil!