Thanks for the response Charles, the reason I ask is because I have many link partners. Most have just used my default URL. I have now added a tracking program that benefits to those who send the most traffic. However that requires them to add a ?aff=14567 to the end of the URL.

I have a very generic keyword that sends me most of my traffic. I am ranked 1 in yahoo, 1 in msn, and 3 in google. I am just concerned if I ask them to change to the tracking URL if its going to mess that ranking up.