"Right-click the Computer icon on the Desktop and select Properties. When the System window opens, click Advanced System Settings on the left and a System Properties dialog box will open.
Click the Advanced tab, then click the Settings button under Performance.
Finally, select the Adjust for best performance option and click OK. If you don’t like the way Windows looks afterwards, revert to the previous setting by choosing Let Windows choose what’s best for my computer in the same dialog box."
You can also right-click on the desktop, select "Personalization" and disable the Aero Theme, and choose directly Windows Classic.
On my old laptop, by tweaking enough settings with the first solution, my W7 looks like this good old XP.