Is the notebook HP255G6SP 379.- worth, and is it good?

It would only need to surf…

You can also get it for 325 euro as a demonstration product.

see: https://www.preiswertepc.de/notebooks/38282/hp-255-g6-amd-a6-9220-dep?channable=e18131.MTQ3MTIy

… I would put another 90 euro on it and get it here:

There's more and more reserve from this!

see: https://www.otto.de/...=748117015

Is there also a 17 inch in full hd and enough memory under 400?

Even in 17 inches there are quite good offers at Otto.de. But I do not think with the same CPU, then it's a bit weaker. But still enough for surfing. Do you have to look yourself!