If you have been a tech long enough to remember DOS/Win3.11, the A+ certification will be a snap. MCSE, even with some experience, is a tougher measure, cuz you not only have to know your stuff, you have to know how Microsoft wants you to know it, meaning the tests are peculiar. Six tests in less than two months=no social life for three months for me, plus i work full time in an IS position. TCP/IP is (IMHO) the measure of how well you are going to do. WinNT Workstation is way easier than Windows95. If you save NetEssentials for last, you will pretty much know everything from studying the rest. I took IEAK for IE 4.0 as my last elective and i thought it was the damn hard, but no failed tests was my (accomplished) goal. Study hard. Take lots of practice tests, and celebrate hard when you become MCSE.
A good place to start the MCSE stuff is with the Sybex Server in the Enterprise book by Lisa Donald. She is an excellent technical writer, and the book is relatively free from the grammatical and factual errors that plague most computer books. It is well thought out, well written, and easily comprehensible. It's approach is global, looking at the interaction of Server with Workstation and other OSs; this makes it easy to understand many concepts that can be a bit bewildering if you start with Workstation or Server. Also most of the exercises are of an instructional nature - the situational questions are in suites on the same theme and these greatly enhance your understanding - there are very few off-the-wall questions - it is always possible to look back and find the answers. Most importantly, if you are studying at home, all the exercises, except those relating to Novell, can actually be performed with only 2 computers, 2 NICs, a cross-over cable, a null-modem cable, and copies of Server and Workstation.
I'm not sure I would write the SITE exam first - Server or Workstation are better candidates, but I would recommend going through the SITE book before you start Server or Workstation. You'll have a much easier time of it.