Download Carbon Copy Cloner or Super Duper (I used Super Duper) and clone your existing Mac hard drive to the new USB Drive.
Format the new drive using a single partition as Mac OS Extended (Journaled) file system. Attach the new drive to your MacBook using a SATA t0 USB adapter or a USB hard drive enclosure. I went from a 250GB drive partitioned into 200GB Mac and 50GB Windows to a 500GB drive with 380GB Mac and 120GB Windows partitions. This solution will allow you to copy your partitions from your current dual boot Mac setup with Boot Camp to a larger drive but re-size the partitions at the same time.
Since you also have a larger drive, you don’t just want to do a sector by sector clone leaving you with a new drive that has the same partitions as the old drive. You have a Boot Camp partition on your mac hard disk so you can’t just do a straight clone of the entire drive using Carbon Copy Cloner or Super Duper (those programs don’t clone the Windows partition). Here’s how I finally got my 250GB dual boot drive cloned over to the new 500GB drive. Installing the RAM was a piece of cake, but moving the data over to the new drive proved much more tricky. So I hopped on NewEgg and got a WD Black 500GB notebook hard drive and 8GB’s of RAM for $150. I’m down to less than 1GB of free space on both my Macintosh HD and the Boot Camp Windows 7 partition. My MacBook Pro has been running out of hard disk space for some time.