You only need switches for the exam, two 3550s should do the trick. If you have the new CCNP Switch Network Academy Lab manual, then that will more than likely be sufficient for labs.
As far as the study material, that depends on your knowledge level. The cert guide is sufficient (as long as you get the errata from CiscoPress.com) if you have knowledge of the topics and just want to prepare for the exam. If you don't have a lot of experience with the exam topics, then you should probably get both the cert guide and the foundation learning guide (which if you took the Network Academy class, you may already have).
The most important thing is tons of lab time. You will have a hard time passing the exam without significant lab time.
I would also recommend checking the Study/Learn page for the 642-813 SWITCH exams as the page contains useful resources and recommended training. Please click here.
Good luck on your CCNP pursuit!
Cisco Learning Network Moderator
Yes, there are two books from Cisco Press: Foundation learning, whcich you should read first and and Cert guide;
SWITCH Lab Manual you can get from InformIT.com
if you at college, look in their bookstore for stuff for Net Academy students or talk to one of those guys;
you will need 2 c3550 switches for lab and maybe one c2950 layer 2 switch;
3550 EMI or SMI; it does not metter too much, you can load EMI on SMI image; works fine;