Thankfully, there's an easy to install image resizer for all versions of Windows available on Codeplex.com. The tool is available in both 32-bit and 64-bit versions. Image Resizer 2.1 allows you to resize any image by simply right-clicking the image(s) and selecting Resize from the context menu, as shown.
Then you can choose the size and options for the pictures, as shown.
You can perform bulk resizing by selecting more than one photo and resize them. Can't get much easier than that!