Help decode strange script file

[securefire]

I ran across this and have no idea what it is.
Can anybody tell me how to decode this?  Is it malicious?

hxxp://www.killerstartups.com/inc/adsensev2.js

 

[y0liny]

nothing here

[SysAdMini]

It's not malicious, but highly obfuscated.

Find decoded script attached. PW: "infected".

Explaining in detail how to decode might take a bit long.

Here are the steps:

-put it into Malzilla's decoder window
-click on "Templates" and choose any browser (navigator)
-run script
-choose the second eval result
-copy the output (bottom window) into clipboard
-replace "____    (O000);" with content of clipboard in top window
-replace "eval  (O0O0)" by "var naa=true;"
-run script
-that's it.