Help With Viewing Doujin

I just got a new computer with Vista on it. I downloaded a doujin from the users upload section and sent it to my flash drive. All my other doujins work fine, but when I try to open up the new doujin, it says I do not have the required program to open the file with and prompts me to either go online to find a program or to select it from a list.

My question is, is there any program that Vista comes with that is able to open the file and if not, what program should I install that doesn't have any virus's.

Use the "Windows Picture and Fax Viewer", it should be on the list when you go to the Open With... window.