Don't know if the X5 is the same, but my 1990 535 IS had what they called hydraulic bushes in the front suspension. They are knackered once the fluid leaks out of them. I had mine done twice over a period of 250,000km.
Just found this http://www.bmwmotorsports.org/BMW_docs/x5align.pdf
look at page 14. It's from the home page of X5 World, "General Info' and Guides #35" then select Alignment Procedures.
Colin.