Eminem has NOT surpassed Pac. In terms of RIAA certified sales (I don't give a shit about what Billboard or the rappers themselves or their record companies say, I can only rely on RIAA), Pac has the following:
2Pacalypse Now - Gold
Strictly 4 My N.I.G.G.A.Z... - Platinum
Thug Life: Volume I - Gold (this isn't always counted toward his total by some people because they're dumb)
Me Against the World - 2X Platinum
All Eyez on Me - 9X Platinum
The Don Killuminati: The 7 Day Theory - 4X Platinum
R U Still Down? (Remember Me) - 4X Platinum
Greatest Hits - 9X Platinum
Still I Rise - Platinum
Until the End of Time - 3X Platinum
Better Dayz - 2X Platinum
Resurrection - Platinum (it should still count since it is basically a Pac album)
Loyal to the Game - Platinum
All of this shit totals 38 million albums sold (even though most people will say 36.5, since they tend to forget Thug Life and don't count Resurrection)
Eminem has the following:
The Slim Shady LP - 4X Platinum
The Marshall Mathers LP - 9X Platinum
D12 Devil's Night - Platinum
The Eminem Show - 8X Platinum
D12 World - 2X Platinum
Encore - 4X Platinum
This totals 28 million albums. Whoever said Eminem has surpassed Pac's sales obviously didn't pass second grade math.
But back to the topic, Eminem's 21st Century sales are 15 million (counting D12 album sales), 50 Cent's are 12 million counting G-Unit (the RIAA online database says 6X Platinum for Get Rich Or Die Tryin' and I'm not just going to believe 50 Cent when he says he sold 11 million... I'm sure that the online database is behind but I have to compare their sales from the same source since it's only fair), Nelly is 12 million counting St. Lunatics. But I believe that 50 Cent is probably the best selling rapper of the 21st century since I'm sure that Get Rich or Die Tryin' has sold more than 6 million.