BulletedList - building the url using a field from the datasourcecontrol

I have a bulletedlist that I have databound to a sqldatasource. I am
using it with displaymode=hyperlink. I set the datatextfield to be one
of the fields returned by the sqldatasource. However, with the url
field, i would like to build the url from one of the fields returned.
Specifically, the url is formed by setting a querystring value to the
id returned in the field:

http://localhost/news.aspx?nwId=533

So the datasource returns 533. How do i set the url field correctly?
I can't use the datavaluefield property since the url is not 533...

Is it not possible? Should i perhaps use an objectdatasource instead
so that i can have full control of what the datasource returns?

Thanks...