My brakes also were crap when I picked the bike up... Then I broke the brakes in (set them it's called in the racing world), and they improved greatly. The deal is, you basically want to cook the top surface of the brake pad while simultaneously glazing the surface of the rotor... (Or drum if it's really old...)
Pick a nice spot of road, 'cause you don't need to be playing in traffic for this.
Take the bike up to 55 or 60, bury the brake in question pretty good, (don't lose traction but apply close to maximum braking) down to about 10-15 mph...
Speed right back up and do it again, and again, and again,(maybe...), What you want to do is cause the brake to fade/fail due to heat. When that happens release the brake and drive normally for a few miles to cool the brake back down. You WILL be pleased with the difference in braking from that unit. Then turn around and do the other end of the bike... Remember to let it go once you fade/fail the brake because you don't want to discolor the disc (It's not REAL critical, because you have to reallly work hard at getting that hot, but don't go crazy... once the brake fades away you've prepped the surface and more heat isn't going to make it any better...)
On a car/race vehicle, you do all the brakes at once, but on a bigger bike, you're better off just doing one brake at a time.
I have a very detailed article about what this actually does and the benefits on my machine at home, and I will post it if I can find it. (Right after someone tells me how to attach something 5 or 6 pages long... hint hint help me out here admin guru's! [smiley=1syellow1.gif]
The bottom line is this, even with a high end brembo or race unit, the braking won't get any better, it will just require less brake pressure to get to it. If the brake unit will lock the wheel up, that's as much brake as you're going to get, period... Past that you have to get rid of more heat faster to stop as fast more times, and that means better discs, which still won't stop you any faster the first time than the traction your tire will support...