This is called brake judder. It happens when you get pads too hot, too fast. The pads sort of melt and smear onto the rotor, causing the vibration. Usually it affects the two fronts, or the two rears, or both.
Usually it's best to replace rotors and pads in pairs (pads are sold in sets of 4 for a pair of wheels). It may seem like only the right front, but it could be both sides, or the rears may be contributing as well.
If you're sure it's the front wheels, I'd get another rotor and replace both sides, and new pads of course.
Are you hard on brakes? If so, you may want to upgrade to some better pads. The problem will usually come back in 20-30k miles unless you change the pad compound.
More on judder and how to fix it:http://rivperformance.editboard.com/brakes-suspension-f6/identifying-and-correcting-disc-brake-judder-t5500.htm
'98 SC Riviera • 268k miles • 298 HP/370 TQ • 0-60: 5.79s • ET: 13.97 @ 99.28 • 4087 lb • 20.1 avg MPG • Nelson Ledges Lap: 1:30
3.4" pulley • AL104 plugs • 180º t-stat • FWI w/K&N • 1.9:1 rockers • OR pushrods • LS6 valve springs • SLP headers • ZZP fuel rails
KYB GR2 struts • MaxAir shocks • Addco sway bars • UMI bushings • GM STB • Enkei 18" EV5s w/ Dunlop DZ101s • F-body calipers
EBC bluestuff/Hawk HP plus • SS lines • Brembo slotted discs • DHP tuned • Aeroforce • Hidden Hitch
'05 GTO • 49k miles • 0-60: 4.8s • 16.9 avg MPG • Nelson Ledges Lap: 1:26