Well, "other apps" is kind of a loose term. What kind of other apps do you have in mind?
No games to date (that I know of?) have multiple threads for dual core/cpu systems (this is going to change in the near future). But if you are comparing a single core 3ghz to a dual core 3ghz you might as well go dual core. I am not from the intel camp so I am not sure if there is a difference in cache, HT, FSB or anything like that with those CPU's... but you might as well get the "better" one.
Ep, glad to see you come back and tidy up...did want to ask a one day favor, I want to enhance my resume , was hoping you could make me administrator for a day, if so, take me right off since I won't be here to do anything, and don't know the slightest about the board, but it would be nice putting "served administrator osnn", if can do, THANKS