.EPS on Finder

Will it open from inside Preview? If it will you can set that to the default by clicking on an eps file, then get info and set the "open all this kind" to Preview.

Have you selected Preview as the option from the list?

Is the file locked?
If Preview is already the default application then it won't activate the check box.

Here's detailed instructions:

1) In a Finder window highlight a file of the kind you want to change the application to open that kind of file.

2) While that file is highlighted, select File > Get Info or press command (apple or propeller icon) + i to get a file information window.

3) In the lower part of the info window there is an "open with" menu with a list of applications.

4) If your application is already in the box then it is the default application for opening that kind of file and you don't need to do anything more. Close the get info window.

5) If the application showing in the menu is not the one with which you wish to open the file then select a new application. If your application does not appear there then select the "other..." and track down the application.

6) If you wish to change all files of this type to open with this application in future, make sure the "change all" button is selected.

7) Close the get info window.

Hi Ninda, iirc you need GhostScript and something else to view .eps files.

Here's one...

http://www.stone.com/PStill/View_EPS.html

From the link...

How to Use Instructions:

In any Cocoa-based application running on Mac OS X that accepts drag and drop graphics files, drop in an EPS file. This will launch the filter service which launches PStill to do the file translation. A PDF image will be placed in your document.

So it looks like you get a PDF, viewable in Preview or whatever.