Comparision of Firewall Products

[MarkusLindingerHamburg @ t-online . de (Lindinger)]

We are about to implement a firewall system for about 500 users.
I checked the papers from Borderware, FW-1, Raptor´s Eagle Firewall,
TIS/Gauntlet and Sidewinder (I suppose, I should contact Cisco too?).

After that, I have a rude survey about their features, but not about 
their proof and abilities in practise. 

Who can give some pros and cons, to get a better background?

Thanks
Markus