boot time is increasingly slow - 1:43 is pretty long, right?

[2Shae]

Get MacJanitor !!

It cleans up your mac.
It worked for me...I also noticed that it got slower after about 2 weeks, but now it's fast again.

 

[w8ing4intelmacs]

Have you tried booting from your OS Install disc (just to compare times)? Also, do you have a bootable external drive? (or even booting off a Mac laptop). I would try that too.

 

[Gurutech]

if you have way too much fonts, your booting time can be significantly affected.

There are many free 3rd party font management program that you should check out if the problem is due to the number of fonts.
Check your font folder