Do you have 64 bit? Have you dowloaded and looked at the MS W7 compatabilty tool?
I have W7 64 bit, and of the programmes you mention, have Photoshop CS4. In 64 bit it installs both the 32 and 64 bit versions. I found that a Canon scanner will only use the Twain interface ib 32 bit, so I launch CS4 in 32 bit for scanning and 64 bit for image manipulation.