I went quad core knowing that most applications will only use a single core. Audio/video encoding is easy to multi thread - so that and any time I am running 2 or 3 tasks at once (almost always) will get a boost.

And the quad core solutions from AMD/Intel are quite affordable now - compared with my processor which ran nearly $1000.

Intel Core 2 Quad Q6600 Kentsfield 2.4GHz LGA 775 Processor Model BX80562Q6600 - Retail

$289 bucks!

It is really only two dual cores stuck together (not a true quad core) but still! So are the $1000 ones.

Amazing.