starkers, can you possibly post a screen shot showing exactly what is being displayed?
Yes, this first shows the missing IP previews in the main window....
... and here is one of the 'Recolor Package' window... with missing previews.
Starkers, I hate to ask the simple questions, but did you reboot after installing and did the problem persist?
I failed to replicate your problem in Win7 32 or Vista 64 with Dreamweaver ip
Yup, did a reboot after installing IP 5 via Impulse in both Vista x64 and Win 7 x64. System has been rebooted into each OS again prior to screen shot.. issue persists in each. However this issue did not exist is Vista x64 with IP 4, though I can not say if this was the case in Win 7 as IP 4 would not install... Impulse recorded the error it was incompatible with the OS.
Hope this and the screenies will help resolve the issue.