Photo Resizing Help (Losing Quality)

Does anyone know how to best downsize an image without drastically losing quality? I don't have photoshop unfortunately. Or, if anyone would be willing to resize the image for me, that'd be great. 

Here's the photo, I need it to be 160pixels tall and 500pixels wide. It is already the correct aspect ratio, just too large. 

https://drive.google.com/file/d/0B2EV3d-qS7AGZUtFNkRkSGYwajg/view?usp=sh...

(Before anyone says anything about the grain, that is because I shot it on a crazy type of film, not because I got all grain-happy in post.)

It is possible that the grain is causing the pixelation, but I really hope not. 

The areas that look more grainy in the original seem to be the areas that look worst when it's resized

http://tinypic.com/r/295qxrb/8

Thanks Sky, I can't see how good the image is because I am on my phone.  But I'll check it out when I get home, if it's at least a bit better than what it looks like when I resize if with Preview, then it should work. Much appreciated.