Each time I'm searching my source code for the word "is", I wish VS.Net had something like this:
Would be very nice, but how about using radio buttons instead of the dropdown, and a graphic "preview" highlighting what's about to be searched?
Sure, radio buttons would be possible, too. The idea behind the combination of a checkbox and a dropdown list was to emulate the look and feel of the "Use [regular expressions|wildcards]" option on the dialog which I think is very well designed from a GUI point of view (and it takes very little screen space). Actually, the "Code and comments" option could be left out as it is the default when the checkbox is not checked. And a "only in strings" option would be nice, too.
I'm not quite sure about the "graphic preview". The way I understand it, this would really make the dialog too big. And the dialog's target audience, developers, wouldn't need it anyway.