I think Microsoft use Aruba for their offices but when they do a show in a big hall and want something cheap and cheerful they use xirrus.
http://www.edugeek.net/forums/attach...-research.docx review that document before you make any decisions on wireless, its the tests that we done in my school to see how each system works (mostly which have been mentioned here).
Trapeze wireless here. We looked at a few other options and found this to be the most cost effective solution.
Supports 802.11a/b/g/n and can even off load the traffic onto a local vlan without having to go all the way back to the wireless controller, we find this very handy for wireless voice.
PM me if you want more information.