There are free (Clonezilla) and commercial (Norton? Ghost) software packages that will do this. However, you need to proceed carefully because I'm sure that these packages haven't been tested on a blended Mac environment. I question the value of saving time versus the risk of doing something like this -- but that trade-off decision is yours to make.
When you ghost, it will save a bit copy of the partition (or drive, but you want partition) off to somewhere, usually another partition or external hard drive. You'll need to make a partition at least the same size (and you can choose bigger if you want) on your new machine before recreating it.
If it were me, I would reinstall Windows to clean out the clutter, etc. You would likely notice better performance in Windows with a new install...
Good luck!
