A quick and free way to do this ?

Something came up and I need to take care of this a bit quicker than opening every single image and cropping in photoshop. I have a folder with dozens of photos of various sizes, some horizontal and some vertical. Because of website layout, I've been asked to give images with a certain vertical and horizontal values that are different for vertical and horizontal images.
I can't do this in LR because it only controls one of the sides at a time and I need it to crop de image to the dimension I need while keeping it centered.
Any ideas ?

In LR's Library module separate the horizontals from the verticals by filtering them by Metadata/Aspect Ratio. Select one of the groups and do Edit/Select All and then in the left side panel, Quick Develop/Crop Ratio, set the desired ratio and they will all be cropped with the crop box centered. Then go to File/Export and export jpgs with your desired dimensions. Next, select the other filtered group and do the same procedure again.

Thanks so much tzalman, that should take care of it. I felt like it was an easy thing for LR to do but I didn't know how.