How can I pass a fixed argument to a view within a panel?
I'm making the assumption your on D7, with views 3, and have Views Content Panes running on your site (Views Content Panes comes with ctools).

So your gonna create your view as you normally would. When it's good and displaying as you want it to, add a display of a content pane (up near the top, under the display, hit the plus sign, select content pane). This will give you access to the "PANE SETTINGS," one of which is "Argument input." Click on this. If you have two contextual filters running on your view, there should be two drop down menus, one for each of your contextual filters.

Set both of these to "input on Pane Config." Now when your adding your views to your panels, your going to use the "View Panes," NOT the "views." Once you add your view pane, you should be presented with two text boxes for your contextual filters, you may set provide the arguments for those here.