Shouldn't my son be talking more at 17 months?

i bet he's fine. at 17 months my oldest daughter wasnt talking much but could tell you what sound a certain animal makes; moo for cow, etc. we got the "Your Baby Can Read" program and within two months she was talking a lot more. the program is a little expensive, but in my opinion definitely worth it. it doesn't really teach them to read, but it teaches them to memorize words and how words are spoken. if you dont want to use this program i would just try to find ways to implement spoken and written words throughout his day - some baby einstein dvds do this (show a word on the screen, a picture of the word, then say the word). also being around older kids who talk a lot will work wonders. and talking to him about everything, like you are doing. my oldest is 3 now and, while she says many words and sentences, her speech seems messy to me - but i think it is just being a 3 year old. try not to worry, though i understand its hard not to.

My daughter didn't start talking conversationally until she was about 3, when her baby brother arrived and she *needed* to talk.  One thing that REALLY helped her is a show called Oobi on Nick Jr.  It's on at 2AM EST but you can TiVo or DVR it, I think we have about 17 episodes, lol.  There are also videos on NickJr.com.  It's adorable and it breaks language down into small, understandable segments while showing the action that the characters (hand puppets) are talking about.  My daughter's vocab exploded when she started watcing Oobi.

One other thing that really helped her is learning the alphabet, she was able to recite the entire alphabet and numbers 1-10 before she started talking!