The original (and best?) Great wall taxi thread from 2006 (with 2007 and 2008 resurrections):

http://www.flyertalk.com/forum/china...web-hotel.html

The pure 2008 version:

http://www.flyertalk.com/forum/china...any-ideas.html

A sort of more general 2008 taxi thread:

http://www.flyertalk.com/forum/china...s-beijing.html

Surely the OP now understands why the collective eyes of many a China forum regular were seen to roll at their posting!

Just as general bits of advice to the OP. Don't negotiate anything at 'PEK' as in the airport. do it downtown. Second the prices quoted previously are still pretty much valid.