Update to this - I added the suggested path to the global environment variable (not my personal one) and all is now working again :-)

Note 1. I didn't copy or move any DLL's - probably these are OK in SP3.

Note 2. If you want to upgrade to Crystal Reports 2008 SP3 it comes as a full install, so you have to un-install your current Crystal Reports first. Once installed I used the CRD / Change Crystal Version application, so didn't need to re-install CRD.