image file size is not same as predicted?

I have created images of two of my partitions. in both instances i used normal or high compression of the tib file.
the tib files are MUCH larger than what was estimated. My C drive went from about 6.8 Gb to 4.7 GB in the tib image. My D drive at high compression went from 14.7 Gb to 14.4 Gb. I might as well not use compression if that is all it will do.
My software is XP sp2 and the NTFS file system. Acronis true image is 7.0 build 584. will it help to update to the lates build?
any ideas?
thanks for any help

 

Is your NTFS drive already compressed?

 

no it is not compressed.
now that i have updated to version 7 build 638 dated Oct 1, 2004, i have other problems.
when i get ready to create the image i get an error "failed to create the scheduled task"....error #1722 the RPC server is unavailable" what is this?

 

You need to uninstall and then reinstall the new build.

 

no response for file size?

 

What's on the drive? If it's full of movies, mp3s, or JPGs, don't expect compression to do much, 'cos these files are already compressed.