well, i'm writing a taylor series program now and it does work, but it's pretty slow because it uses the symbolic d( function.
so it just calculates the derivative of the derivative of the derivative etc.
and that's pretty slow if you want to calculate the 20th term

is there another way to calculate the nth derivative of a function?
any help would be appreciated 

another question, could the functions of omnicalc, symbolic and prettyprint be integrated into the os using a patch?

It's certainly doable. But I'm guessing that most people aren't too concerned with integrating such features natively, as they already work fairly well as simple parser hooks and MathPrint is a decent enough replacement for Symbolic. Finding someone with the intersection of motivation and OS patching/hooking skill (unless that someone is you) could be tough.

I've never actually used PrettyPrint. What about it is better than MathPrint?

and it doesn't crash every !@#$% time i use it

i really like symbolic and prettyprint because they're just so convenient and it's a nice replacement for people who loathe mathprint (mathprint is the devil)