CS3 can do 16-bit edits, has Bridge, and has a complete version of ACR 4.
PsE9 can only do 8-bit edits, and has a very truncated version of ACR 6.
Put another way - PsE9 has less than 1/2 of the capabilites CS3 has.
Plus if you have a legal, registered copy of CS3 you can upgrade to CS5 today for just $199 (the upgrade price), or wait and upgrade to CS6 for the upgrade price (10 or so months away). what is Photoshop | Adobe Photoshop CS5