It's a bit more complicated. You can technically just take one certification and BE certified in server 2008. Check out the MCSA 2008 here:
http://www.microsoft.com/learning/en/us/mcsa-windows-server-2008-certification.aspx
With these three certifications you'll have your MCSA for 2008.
As for study material i would suggest the Microsoft Publishing books, make sure to get the second edition ones since they've updated the exams. Those books (depending on the exam you want to take) with a lot of lab time will get you prepared to become certified.
You can also check out these free labs: http://technet.microsoft.com/en-us/virtuallabs/bb512925
Those labs are free and actually allow you to do whatever you want.