This was discussed in a feature request thread a few weeks back. I don't claim to really understand everything said in that thread, but it was explained that this is not possible. Basically, you don't receive that information until the connection is made. You can probably find the thread in the first page or two of the feature request forum.
It is possible to access the information via the 'conditional accept' mechanism, which was
pointed out in the thread you're talking about. There appear to be
some drawbacks to this though, at least on Vista upwards.
