It's simple (enough): Your D7000 came with ViewNX2. Install it and use it to 'convert' (really export, as it leaves your NEF's alone) from NEF to 8-bit TIF, as Elements will open and view
but not edit 16-bit files.
So doing will allow you to open the .TIF in either ACR or directly into Elements 8.
OR you can go to the newest Elements. PSE9 allows you to install the most current version of ACR, which supports the D7000. You can buy it from
Amazon, currently $79. A $20 rebate nets your final cost to $59, but last week they were featuring it at $59/$39. IDK when or if that promo will repeat. Even the current price should be within reach for a D7000 owner, unless you broke the piggy bank to buy it.