No, you need a projector housing as a reflector that's used with halogen bulbs doesn't provide any cutoff needed for a xenon bulb. If you simply replace the lamp, you'll just spew light all over the place. While it will be brighter, you'll just tick people off by blinding them.
And since it was mentioned, I'll just keep going...
You have two types, your run of the mill low-beam setup, where a halogen lamp is used for your brights, or bi-xenon, where the same lamp is used for both low and hi. Hi-beam is accomplished by either a flap that flips out of the way, or the whole bulb shifts down. If you retrofit, as mentioned, it's not the cheapest option, but do not, under any circumstances, simply replace the a bulb with a xenon bulb within the same halogen housing.