Hey Sam,
I don't have much knowledge, but I'll offer what I can as I've recently just gone through the purchase of my first road bike.
Fit and comfort are key components of a road bike purchase, as anyone will tell you...that said, if you're looking at going REAL entry level
(e.g. just borrowing someone else's bike or buying the cheapest used thing you can find
) it may be less of a consideration.
Shimano components from top to bottom:
Dura-ace
Ultegra
105
Tiagra
Sora
(I think
)
and on down the list
I'm not going to recommend what I think you should get component wise because I don't know how much you want to spend. My bike was a good deal at $1400 and has a combination of DA, Ultegra, and 105.
A good brand for value to look at is Giant. In my searches, they really had the most for the money. That said, it's the time of year when last year's models are being closed out, so you might find a real gem in a different brand. I know Local Ride in Maple Ridge even has one or two 2005 models on their floor that I bet they'd be glad to be rid of. You may even talk to the guys at Overtime Sports in Coquitlam as they could potentially bring in a bike that's left over that the distributors want gone for a good price. They offered to do that for me last year but had a hard time finding the right size for me.
I'm not sure how much you want to know or what you want to know about...
Other places to look for used bikes are of course Sport Junkies
(although I find stuff to tend towards overpriced considering a lot of it is used and...junk
) as well as that place on Dunbar whose name I can't remember. A friend of mine was telling me about a place around 8th and Burrard that's supposed to be good for both used and new bikes as well. He bought a pretty decent bike there that he rode a HIM on for $500 apparently. Cant' remember the name, though...
I hope that helps a bit, at least.