bendsley:
A lot of the things that were involved with Exchange 2000 carry over to 2003.
I would also like to stress that Exchange as a product is FUCKING EXPENSIVE (if you don't know, I do.. I had to put in a purchase order for the non-enterprise copy): It cost my company many thousands of dollars, and we will not be expecting to upgrade for a number of years.
liquidlight:
Exchange 2000 Server 24seven is a good buy if you can't go on training. It is
not the end all and be all, but it will teach you a number of things about administering a server.
The best dead-tree book though would probably be right from the horse's mouth:
MCSE Microsoft Exchange 2000 Server Administration Readiness Review; Exam 70-224 with CDROM.
If you can, take the exam; It will show your employer that you have what it takes.