The Xbee socket is powered from the main regulator, which can source 500ma. If your radio was having trouble drawing current, you’d probably see strange behaviour on the rest of the board. Are you powering anything power-hungry at the same time as the radio? What kind of antennas are you using? Xbee units have a default power setting of “high”, have you changed that or are you using the default configuration? Have you tried monitoring the current while the radio is transmitting?
For what it’s worth, I have used lots of Xbee and Xbee-Pro modules, both 2.4Ghz and 900Mhz, and there are a lot of different factors that influence the signal range. What kind of range are you currently getting and at what frequency?