Just a quick note that the newest drivers did not play well with my intuos3 and photoshop CS4. If you have installed these drivers and find that photoshop intermittently stops registering pressure sensitivity then you should roll back to older drivers.
Got some new hardware (mobo and CPU) and after reinstalling Win7 (32-bit) I grabbed the latest wacom drivers from the 22nd of November and reinstalled photoshop CS4 Extended. But photoshop would randomly lose pressure sensitivity on some strokes. But with the wacom preferences open I could confirm that wacom was indeed registering the appropriate pen pressure by looking at the little pressure graph while photoshop was running.
I went through every trick I know for making windows play nicely with my tablet, shutting down other services such as the Windows Tablet stuff to no avail. I uninstalled everything I could and reinstalled everything. Still losing pressure sensitivity on random strokes. I even downloaded the trial of CS5 to see if it was an issue with CS4. Same deal.
After 20+ hours of troubleshooting I rolled back to the older driver from March and found my tablet and photoshop working as they were designed to.