Will Converting High Rate Songs affect the original?

I have an old 4gb iPod nano and want to put a few of my favorite artists on it so that when I have it on my docking station I can still use my iPhone 4s
When i do this it goes over 4gb so I clicked the option to convert to a lower rate song
Obviously this will change the quality of the song when it is on the iPod (which doesn't matter because it isn't the main one i will use) but will it affect the original file on my PC and on my iPhone?
Because I still want the original high rate songs on there because they have much higher memory
Please answer!

Good lord it doesn't touch the original! That would be awful wouldn't it? No you're safe.