Learning Windows Server 2003 and Linux

Greetings!

I am CompTIA A+ and recently Network+ Certified individual trying to gear up my skills to break into IT. I was hoping to get some tips on how best to go about learning Windows Server 2003 and Linux.

I am particularly worried about Linux seeing that there are quite a lot of distributions. I am considering studying for a CompTIA linux+ Cert but I am having a hard time deciding on going for a Red Hat Certification instead.

Being A+ & Network+ Certed, is there a need to pursue a Server+ Cert? and what is the best way to learn about Windows Server 2003? Up until now I just pick up books to read.

Or should I put these on hold and fire on to MCSA?