OT: processor fan question

[Vaughn Treude]

Hello everyone:
Here's a hardware question for you.  I have a machine running a 900 MHz
Athlon.  Its processor fan is making lots of noise and sounds like it's
about to die.  I tried to find a new Socket A-style heat sink at Fry's
but they didn't have this ancient piece of hardware.  On the good side,
the dying fan on this heat since is a standard size (60 mm), and is
fastened to the heat sink with screws.  Is there any I shouldn't just
replace the fan with a new one?  The reason I ask is because the old fan
has weird blades - smaller than on a standard fan, and more of them. 
The new fan, however, seems to blow much more air than the old one does
(this was with its back to the floor, to simulate the restriction of the
heat sink.) My theory is that the smaller blades may make the cooling
more uniform, but I don't know if a 900 MHz processor is all that hot
that I even have to worry about it.
Vaughn