It seems that the Adobe Camera Raw 2.1 from Photoshop CS can be used in Photoshop 7 by patching the free update from Adobe and installing it into Photoshop 7.

The instructions and patch can be found in this site:
http://colblair.nm.ru/acr.htm

This was reported in dpreview in this thread:
http://forums.dpreview.com/forums/re...essage=7703596