I agree, go with the i5. It's newer architecture will surely give you what you are looking for in terms of performance and is easily overclockable. Plus, the Q8xxx series aren't exactly the best chips for OC'ing (if you go that route).
Just built a new i5 750 system for my flatmate, Happily overclocks automatically on the fly up to 3.2ghz thanks to a good motherboard choice.
After seeing it running my own Q6600 @3.6ghz will soon be getting replaced.