RAW files usually won’t open like JPEGs because they are not standard image files. They contain sensor data from the camera, and each camera maker often uses its own RAW format. To view or edit them, you need software that supports your specific camera’s RAW files.

Common options mentioned include the camera manufacturer’s own RAW software, Adobe Lightroom, Photoshop with Adobe Camera Raw, Darktable, Aperture, Picasa, ACDSee, and DxO Optics Pro.

Which one you need depends on your goal:

• Just viewing: a simple RAW viewer may be enough.
• Editing/converting: use a RAW converter/editor such as Lightroom, Darktable, Photoshop/Camera Raw, or the maker’s software.
• Batch processing: dedicated RAW processors can handle many files at once.

Your i3/4GB PC should be able to open RAW files with compatible software, though performance may be modest with large files. The key issue is software support for your camera model, not just the computer hardware.