Hard drive overkill

Hello,

I recently purchased a 500GB hard drive for my Sony Vaio computer. Apparently, this model (VGN-FE670G) can only support up to 100GB, so instead of the full 500GB I was expecting, I am getting only 120GB. Is there anything I can do to utilize the remaining memory? Maybe re-partition/create disk drives?

PS. Despite what you might think :) I did ask several of Sony's tech support people the maximum hard drive capacity of my computer before purchasing the new one. I got no useful response besides "Sony does not support and will not provide help with hard drive replacement by end user"