notebook and tablet is different products. different functionality, different boot options and software handling. Android inherited Lunix way of handling and installing software, and that is great difference with Windows.
Asus Transformer great tablet which can be transformed into notebook easily . New microsoft tablet also has similar keyboard and runs windows 8 and has huge SSD hard disk.
Size of screen depend on what you need, watching movies on 7' and 10' very different story.
Also sound quality provided by different tablets not the same usually 10' tablets have better sound quality.
I use Sumsumg Note it is not much more costly then Galaxy S, but quality wise totally different phone. Not getting hot when charging battery and running wifi hot spot, but GalaxieS will get hot and need USB fan for cooling. Screen on Note better too, super amoled - superb screen.