website design - How do Windows users interact with scrolling panes?

Let's say there's a website with a row of gallery thumbnails you can click on. It looks like this:

As a Mac user having always used either some sort of trackpad (built into the MacBook, or a Magic Trackpad) or even Magic/Mighty Mouse where you can scroll in all directions, my gut is to move the mouse over the images and scroll horizontally.

What about Windows users, though? I wonder if their first reaction is either:

1. Where the heck are the scrollbars?! I give up.


2. Ah I see there are more images out of the view, I'll just scroll horizontally.

My goal is to make it obvious and intuitive for all users, regardless of platform.