Unless your computer has a 2gb or 10gb ethernet port, then the 1gb is all you need.
Also, remember the speed is shared among all devices, so if you had a single device using the entirety of the 2 gb, then all other devices would be getting no internet at all.
My computer is a hand built system, each piece selected specifically for this build, it's cost, 360, that doesn't include ram/cpu/video card/case/power supply/kb/mouse/monitor. I have a Netgear CM2000 and a RAXE300 router, to go along with the computer build, and I can take advantage of that kind of speed. I say this, because 99% of the computers out there CANNOT take advantage of that speed.
The bottom line, while most computer cannot take advantage of the 2gb speed, that doesn't mean it's wasted, because that speed is shared among ALL of your devices.
