Well, unless you plan on doing some serious OCing, I'd say stick with stock. The only reasons that I can think of for going for a 3rd party HSF are for more headroom when OCing, or for less noise.
But hey, if you think you might want to OC in the future, and replacing the HSF seems like too much of a hassle, then go for it. You only have your money and your warranty to lose.
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200,000 miles or bust!
<pre><font color=white>Antec Sonata, 2x120mm fans, P4C 2.6GHz, Asus P4P800Dlx,
2x512MB CorsairXMS3200C2 in DC, Leadtek A6600GT TDH, 2xHitachi 60GB in RAID1</font color=white></pre><p>