It's not like there aren't plenty of other options out there. IBM Thinkpad's have excellent keyboards- I'm not sure if the NetVista is similar, but I can understand it feeling too heavy. I still think investing in the desktop is the better option.
I'm not sure if you used an iBook G3 keyboard. They are very "light" I guess but in my opinion they're way too light and most people I know don't particularly like them. They really just don't have a quality feel to them, lack good control, and if you don't hit the button squarely in the center the keys bind up.
The NetVista keyboard is the keyboard they provide with all Windows 8 Lenovo desktops and is pretty much identical in appearance to the black IBM keyboards that came with the Black Windows XP IBM ThinkCentre's
Looks like this its on the bottom:
NOTE: NOT MY PICTURE!
