I bought the DP-4000 in 2007... eight years ago !
It gave me great satisfaction during these eight last years (with the software included runing under Windows XP).
Past month I changed my computer and moved to Windows 7.
Great great problem : the old software was not recognizing the USB port where the DP-4000 was connected.
With Chris advice, I uninstalled the old version of the software, downloaded the new software, installed it on my new computer, and... ALL IS FINE !
Very great material and very great software for VERY GREAT MOMENTS OF PUMPING !

Thanks Chris, thanks CTC !

(Review from an old frenchy!)