Macbook Pro Retina external HDD First of all, I haven't used any Mac computers before. And now I'm considering buying a Mac book pro retina 15 with 256 or 512 Gb SDD as my travel laptop. I need to run both MacOS and Windows 7. The problem is that 256 and even 512 Gb is not really enough for me, so I'm considering buying an external HDD. I'm thinking about 2.5 inch 7200 rpm HDD with at least 750 Gb capacity with an enclosure which supports USB 3. I'd really like it to be very portable so I can use on a plane. It should be both accessible from MacOS and Windows. At first I thought that I would install Window 7 on this external HDD, but after reading some blog I found out that it is almost impossible because of Windows limitations. So my goal is to insert both OSs on the internal drive and keep the rest on the external HDD. 


Can I get some advise about this setup? 
Any pitfalls like driver problems on Mac? 
Any suggestions on particular hardware and software? 


My goals are: portability and speed.
You can't run Bootcamp from an external hard drive, but you can install Windows via a virtual machine (MV Ware or Parallels are the best known). If you install Windows on the internal drive you have the option of booting from it directly or using one of the VM machines while running Mac OS.

As for the hard drive size you should consider the 768GB drive if possible. The drive space goes quickly and isn't upgradable. (Well, it is, but AFAIK nobody makes larger or faster replacement drives.)

The OSs run independently of each other, so you don't have to worry about cross-contamination. When running BootCamp you can't even see the Macintosh partition.

In my experience it works as well as can be expected considering the limitations of running software on hardware that wasn't specifically designed for it.

Good Luck.