I too still have two DELL M90 LAPTOP Computer WORKSTATIONs using WIN XP. Both my home and RV setups are almost the same configuration using the DELL DOCKING STATION and same setup at both locations. All I do is remove my DELL M90 from home location and use as is at the RV location. There is almost no difference in operations at either place.
I will continue to use this until I upgrade my LAPTOPS. They are getting old as well but works great... I will be looking for more OFF-LEASE DELL M6700 series or newer high end DELL XPS Work stations
I doubt upgrading to WIN 7 or WIN 8 will do me much good as all the software I have will probably not work anyway...
For me I think looking for a new Workstation LAPTOP that supports my computer needs already working on WIN 7 or WIN 8 is my way out of this.
Roy Ken