Both hhnngg1 & canam73 make excellent points. -- The "looks" of your bike is HUGE...it becomes part of you. You can always switch out components later but your bike frame is there to stay...make sure you love it! As far as Shimano shift levers: Canam73 pin pointed the differences. THe sora is more of a thumb shifter which is easy to shift from on the hoods, but sometimes can be annoying when you are riding in the drops. If you had to choose I would go with the Tiagra all the way, but I like paddle shifters...it's up to you and what feels most comfortable! Test em both and see what you like, and remember if this is the bike for you, can can ALWAYS upgrade your parts down the road. -- Have Fun, and post the pics when u get one!!!

http://brandscycle.com/product/shima...vers-16024.htm
http://www.amazon.com/gp/customer-me...e=UTF8&index=0