I don't think you'd ever look like an idiot on a Cannondale. I think this is a good entry-level bike (better than most, actually), but I'm not an expert. Just married to a Cannondale fanatic. I ride a Specialized Ruby Comp myself, also bought on Craigslist at a huge discount from someone who was done with riding. (There was a guy involved. He broke her heart and she never really liked cycling anyway...win for me. She would have given me her Sidi shoes, too, if they'd fit me.) She had 104 miles on the bike, according to the computer she left attached to the handlebars.
You can get a really good deal buying used.
Check the bike for scratches, cracks in the frame, and stuff like that. If it's been in a bad wreck or generally mechanically abused (the owner didn't maintain the chain, crank, gears, and all that), it could cost you a lot of money to repair and negate any savings.
Good luck and welcome to TE!
Roxy