Yeah, they will all have some sort of a compression. In the previous PC, I have found that the fastest backup/restore speed is when using the default compression. But on this new PC, I have found that the sweet spot is another compression level higher, maybe because the CPU is a lot faster than the hard drive.
If you are using XP, there is another thing you can do the make your images slow.
You know, it's the Registry that's resposible for most of the problems related to Windows. If you could isolate Windows from programs and user profiles, you can make your images smaller and easy to manage. When the user profile is in another partition, when you restore an old image, you will still have your latest user preferences saved.
You can use nLite to make a custom XP CD which has different programfiles folder and documents&settings folder. But test it before you install - mainly with the drive letter. Windows doesn't give you the results you expect on the first run.