Postgresql 8.4 installed, but no spatial extensions?

[4Hfather]

Followed tutorial to install Postgis.  Ran Applicaiton Stack Builder, but although there are several application trees showing thereunder, cannot see Spatial Extensions, nor Postgis anywhere.  Should I back down a couple of versions?  The installer for version 8.4 seems a little different than the methodology from the tutorial suggests.

[Indrid Cold]

The tutorial was written for v8.5.1... givr that version a shot and it will be there.