My Compaq Presario (SR1 299AN) is so LOUD! The computer fans often
turn on, and the sound can be overwhelming. I'm not sure why, but it
particularly goes nuts when I open microsoft word and type manually -
and I'm forced to type because the racket drowns out dragon naturally
speaking ( I have RSI and would prefer to use speech recognition).

And yes, I often clean them to remove dust, etc. So my question is:
what can i do to fix this? Can I replace the fans with something less
noisy and/or constant, etc?

thanks in advance