Western Digital Passport 250Gb external drive and MacBook Pro

Hello,

Has anyone with the 15" 2.2ghz 120Gb hd MacBook Pro able to connect this Western Digital Passport 250 GB external drive to only 1 USB port and has it working?

I intend to buy both of these hardwares, but was told that I may need to get the extra Y-cable that can connect to 2 USB ports of the MacBook Pro since only 1 USB port may not have enough power to work the WD external drive? The WD drive comes with only 1 "standard" USB cable.

Thanks.