more tax cut questions- bush speech

[Leslilake1 at aol.com]

bush tonight says a waitress with two kids making $25,000 - if she tries to 
better her situation, every dollar she makes over $25,000 is taxed at 50% - 
sending the awful message - "you can't get ahead."

can this be true?  how?  do the two kids matter in this calculation?  
something smells dubious here too...  (I am roughly in this income bracket 
and usually soc sec. taxes roughly equivalent to income tax come april, also 
usually wind up sending check with my return...)

les