I've taken a couple of those MCP tests in the past... a couple years ago, in high school, there was a class for it and the school covered half of the test cost, and then after i got out of high school, i took another one of the tests and it cost $120 just to take it, pass or fail.
but to their credit, after you pass a set of 4 of them, you're what's called MCSA (microsoft certified systems administrator), and once you pass 7, you're MCSE (microsoft certified systems engineer) which is a pretty good certification to have. but beware... the tests are pretty hard.. the first one (win 2Kpro) i passed, but barely with a score of 680, while the minimum to pass was a 660, and the next one (win 2K adv. server) i failed, but it was close... 640; 20 pts. short of passing, which is only one question.
basically.... they're fairly good to have, but you'll want to get at least MCSA which is a set of 4 of them, and they're hard, so study braindumps before you take it, they really help, because the questions are long and confusing sometimes.