I'm getting a laptop but i wan something slim n high speed any help ? im an idiot in this field !!?

my budget hopefully is up to 2.5k n oso the latest version any suggestions ? mi sis had suggested me to get either acer,toshiba or ibm .. i hope i can find one as light below 2kg .and something i can find within e retail shops like harvey norman,courts or best denki ! thanks ! all suggestions r welcome !