Validating URLS? why???

I just noticed one thing, when I add "
http://www.projectwonderful.com/advertisehere.php?id=27098&type=1" to my
site, my site isn't xhtml 1.0 transitional anymore.
(
http://validator.w3.org/check?uri=http%3A%2F%2Fjagf.net%2Findex.php%3Fsid%3D4770dfc03192f114808792f20258e384;accept=text%2Fhtml%2Capplication%2Fxhtml%2Bxml%2Capplication%2Fxml%3Bq%3D0.9%2C*%2F*%3Bq%3D0.8;accept-language=sv-se%2Csv%3Bq%3D0.8%2Cen-us%3Bq%3D0.5%2Cen%3Bq%3D0.3;accept-charset=ISO-8859-1%2Cutf-8%3Bq%3D0.7%2C*%3Bq%3D0.7
)

The thing is, I really want my site transitional, but ofcourse I have no
idea how I should fix a link since it isn't me that own projectwonderful.com
..

So I want to suggest, please don't validate URLs since if I change something
in the URL, the URL will become broken