Time in the top 2 at the time of writing:
Federer 424 weeks (302 weeks number 1 + 122 weeks number 2)
Nadal 403 weeks (141 weeks number 1 + 262 weeks number 2)
Federer is going to be number 2 or higher for at least a couple of months more. And possibly at other times going forward. But you have to think that Nadal will win out in the end, given that there isn't much of a gap currently.
Federer 424 weeks (302 weeks number 1 + 122 weeks number 2)
Nadal 403 weeks (141 weeks number 1 + 262 weeks number 2)
Federer is going to be number 2 or higher for at least a couple of months more. And possibly at other times going forward. But you have to think that Nadal will win out in the end, given that there isn't much of a gap currently.