Reversing an entry card - How to find out what type of RFID hardware I need to read the chip?

You only need one RFID device, its the Proxmark3. There are many protocols and frequencies used by RFID and the Proxmark3 tries to support all of them. It is open source hardware and software and breaks every commercial RFID card I know of. The real problem with RFID is that you have a very limited power usage so you are forced to use weak crypto systems. Often times they rely upon security though obscurity, and the Proxmark3 is designed to overcome this.

Might sound glib, but often a quick Google gives information on which companies use which card providers. I would always use this first if the company won't tell you before the test.

Have a look at Major Malfunction's extensive back catalogue of rfid presentations, as he discusses issues such as this.

Try http://www.google.co.uk/m/search?q=major+malfunction+rfid