When you installed older versions of Photoshop, you could see thumbnails of PSD files when in Windows explorer when you viewed the folder as Thumbnails XP (or as various size icons in Vista).
For some unknown reason, Adobe removed this useful feature in recent versions of Photoshop. Therefore, if you get a new machine and install a new version of Photoshop you don't see the thumbnails. 
Instead you see something like this:
The solution is a little tricky; get someone to help you if you're not comfortable.
e-Mail me if you can't find a copy, I see if I can find you a link.
I had to reboot before it would work, but once I did I saw this instead:
Or you can use the little pull-down arrow next to the word "Views" and change the size of the thumbnail icons. The ones above are "Large Icons"; these are "Medium Icons":
And these are "Extra Large Icons":
Note: If you click on the word "Views", instead of the pull-down arrow, it will cycles through the view choices.
Maybe the reason Adobe removed the DLL was to encourage you to use their dialog box when opening files, etc.:
Much of the time I perfer the features in OS dialog (red arrow above), but I need to experiment more to explain this. The key thing is, once you install the DLL, the thumbnails also appear in the "OS Open" dialog and you see:
If you see something like the view below instead, click on the "View Menu" icon (red arrow below) to change the view to "Large Icons" or Thumbnails:
Suggested next choices: