New to Java

hey I just made a game in swing using Eclipse and I converted it into a jar file. The game works fine when I run it through the jar file on my computer. I took the jar file to my dad's computer and double clicked on the jar file and it worked fine. However, this game is for my girlfriend and when i brought the game to her house and put it on her computer, it had become a winrar icon. So now she can't play the game i made for her:( If i double click on the winrar file it just goes to the screen about extracting contents etc. So why did it change and how do I fix it so she can play it? I looked in program files->java on her comp and there was 1 folder inside and it was jre1.5.0_15 i think. So what does she need to download in order to play my game? or is there something else wrong?

I really appreciate any help you experts can give me, spent ages working on this for her so it's a real pitty that it's not working :(

Cheers