Shame- I know bugger all about Windows 7 and have had little exposure to it, though the process of setting up sharing will be the same technically as earlier versions, just with a different interface. Well, you need to set up sharing on the PC, bearing in mind that when you do so it won't share all the folders automatically- you will have to specifically share the folders you want to see, by going to Properties and making the folder you want (ie the one with the pictures) a share point (at least you do on my XP machine). At this point you can enable network users to change the files within it but you don't need to do that as all you want to do is copy them off.
So, you will have file sharing on on the PC, the pictures folder shared, and it connected to the Time Capsule with an ethernet cable, as will be the Mac.
On the Mac if you open a Finder window you should see the PC appear in the sidebar on the left under "Shared" appearing as its networking name that you gave it when setting up the file sharing. If you click on it once you will see a button that says "Connect As..." to the right. Use that and connect to it as your DH or whoever the admin username of the PC is, with the appropriate password. You will then be asked which share point you want to connect to- choose the pictures folder and you're on.
If for any reason that doesn't work you can go to "Connect to server..." at the bottom of the Go menu in the Finder (armed with the IP address of your PC- for the sake of argument I am going to pretend it is 192.168.1.9) and then type in this:
smb://192.168.1.9
and connect that way, using the username and password as above.
That's it really. I suggest you strategically put a destination folder from you Mac into the sidebar along with Documents, Downloads etc. It's easy- you just drag the folder there from a listing on the right, being careful not to move it to one of the ones that is already there (you get a blue line instead of a blue highlight on one of the icons when it's ready to go) Then it will be very easy to drag stuff from the folder on the PC to the destination folder on the Mac.
Good luck 