USB 2.0 Ports for WD My Passport 1TB USB 3.0

Hi this is my first post and also my first time buying an external hard drive . Currently I am thinking of buying this device but I am wondering how much slower will it run on my standard USB 2.0 ports compared to an USB 3.0 port. Also will I need an adaptor to run this device on my computer? Like I mentioned before this is my first time with something like this so if you need more information on my ports themselves I will be happy to add some.

*note, I would also like to know how reliable is this device exactly? Can I expect it to last me for years to come if I keep it safe? 

*Another note, also if the difference between a USB 3.0 and USB 2.0 is drastic enough is there any way to upgrade my ports? Or is it something you must decide on as you are building your PC? Once again I have never really messed with my ports before so please forgive me for my ignorance. 

*One last thing, my OS is windows 7 

Thank you for your time

   -Ryan 

http://www.everythingusb.com/comparison.html

here’s the answer to your question.

Also if you have a usb 2.0 port, the usb 3.0 will work however it will only follow the speed of the usb 2.0 speed. For you to be able to get the speed of usb 3.0 you need a usb 3.0 cable and usb 3.0 port. And these speeds are burst speed and not sustained.