Beginner rider needs help.

Besides the bike I would plan to buy:

Padded shorts
Helmet
Shoes
Floor pump
Chain lube

Small bike bag
Extra tube
tube patch kit
Co2 Inflator or mini-pump
Water bottle Cage and bottle

That should get you started. Then as you have the money to spend you can buy things like a bike computer, jerseys, etc.

So I priced that all out, didn't go for the top of the line stuff but more mediocore and I have a few of those items, I have the following listed:

Paddd Shorts - $40-50
Helmet - I have
Shoes - $50-75
Floor Pump - $20
Chain lube - $5

Small bike bag - $10-25
Extra Tube - $5-10
Tube Patch Kit- $5
Co2 Inflator/mini pump - $15
Water bottle cage - $10
Bring a total of $160-$215

Do those prices seem resasonable?

Also with that it leaves a bike for around $800 or so. I was looking online and it looks like some of the MSRPs in that range are: Trek 1.1, Trek Lexa S (older model), Trek 1.5 (older model), Giant Defy 3, Cannondale CAAD 7 Sora, Cannondale Synapse Alloy 7 Sora/Tiagra (Either One).

As far as I can tell, the difference is in the Shimano Components that are used. I am wondering now what are the major differences between the different sets. Everything I see keeps recommending the 105, what seperates the 105 from the Tiagra or the Soras? Will I notice a difference between the sets being that I am new to cycling and road bikes?

One last question, would it be worth it to pay the extra $300-$400 for a complete 105 bike like the Trek 2.1 or the Giant Defy 1?

Thanks,
Adam

You've got to go ride them to find out if the difference is noticeable to you. Basically the pecking order Shimano wise for components is 2200/2300, followed by Sora, then Tiagra, then 105, Ultegra and Dura Ace.
Have you looked at last year's models? Although the window of opportunity is small now, I saw a few weeks ago a CAAD9 with Tiagra that I could have picked up for ~$800.

Ride bikes with the different components to see if you can notice the difference. If you can notice a difference and want the nicer components then it is cheaper to do that now, than buy the bike with the cheaper components, then upgrade.
My bike has a 2300 font der., Sora rear derailleur and 2300 levers. It works fine. Buy from a good LBS and some of them will throw in adjustments for life, which will keep everything runnning sweet anyway.

Good luck.