Put all the photos you want to resize into one folder.
Open Photoshop, go to File >> Scripts >> Image Processor. Select your folder of photos, select 'save in same location' (it will give you a new folder within your original folder), tick 'save as jpeg', quality 12. Under 'Resize to Fit' enter the size you want the new photos to be, then click Run.
You'll get your original folder of photos untouched, with a folder within that of resized photos to the size you have selected, which you can then do whatever you like with. Easy - but shout if you need any help!