portable drive to use in the field
I would like to buy a portable drive to download my images while still out in the field and I am confused by all the details. I would like a 320GB or 500 GB capacity. I would like a fast download rate and of course, that it support RAW files. I need to be able to use it any where in the world (110/60 & 220/50 power). At home I have a PC with Windows XP and a laptop with Windows 7. Please advise on how I can sort through all that is available. Also please recommend and/or tell me what you use. Thank you!