How to change color space from RGB to Adobe1998

I set up my photoshop 7.01 with the default color space that was offered.
I did not pay attention to the fact that my digital pics are taken in adobe1998.

Now, I have 290 .NEF (Nikon Electronic Format, or proprietary Nikon RAW) files, which I can all view in Photoshop, thanks to the appropriate plugins. But every time I open a file, I get the message about the different color space and do I want to:
- open the image with the embedded color space
- conver to the workspace color space
- no color manage

The thing is: I'm trying to create actions to batch-process these files. Because of this prompt at the opening of each file, I cannot automate the actions.
So, my question (at last): how do I change the color space to match that of the files?
Thanks.

unless I'm misunderstandnig you go to view...proof setup...custom...Adobe 1998 is in that list.