The Eagles' WRs have exceeded all expectations this season (even if they were low expectations). Despite this I would agree that a true #1 WR is still needed for this offense to take-off. I would also argue that not trading for Roy Williams, and at the Lions' asking price, earlier this season was a smart move by the Eagles.
The Cowboys offered up 1st and 3rd round picks in 2009 for Williams and are paying him a guaranteed $20 million in salary. What have the Cowboys gotten for their hefty investment? Not much. In 6 games with the Cowboys, Williams has caught only 11 passes for 161 yards and one touchdown.
In comparison, during that same six game stretch Kevin Curtis (returning from injury) has caught 26 passes for 288 yards and one touchdown. Not spectacular either, but better than Williams.
If given the choice, I still prefer Curtis over Williams.