You can do what you want but i personally advise users to stay away from iTunes for photo/contacts syncing. What you just stated above is part of the reason why.
I use an app called Dropbox for my photos. Create a free account on your computer by going to the website. Download the Dropbox folder.
Drag and drop any pictures on your PC to that folder.
Download the Dropbox app from the AppStore on your phone, open it, and sign in. Any picture you placed in the Dropbox folder on your PC will show in the Dropbox app.
Vice versa to. In the Dropbox app, tap the "Uploads" button, choose any picture in your camera roll, and tap the upload button, then those pictures get transferred to your Dropbox folder and can be viewed in the Dropbox folder on your PC. (please upload photos from camera roll while on WiFi and NOT 3G for good picture quality)
I know that is not what you were asking. I just thought I would let you know a more "reliable" way to keep pictures in sync with iPhone and PC.
Any way............Your pics are still in your phone no?
Well, usually when you first plug in your phone a pop up box pops up, and you can choose to transfer pictures with one of those options.