I'd go with nothing less than 3k for speed. For some, even that's a bit slow.
the new Core2s are way more efficient than the older cpus, you cant just compare the clock speeds like that
My 1.6ghz Core(1) duo kicks the ass off my old 3.4ghz Pentium 4. Any Core2 is fine for all home/office tasks but serious gamers will want to look at the higher specced chips.
Thats a good chip you have there and it will be a definate jump from your old one. Its one of the new ones with the 45nm process so it will stay nice and cool. If you are feeling adventurous, its possible to overclock one of these to 3ghz easy, and 4 with sme work, although unless you are a hardcore gamer, you dont really need to.
As for the moterboard you mentioned, i cant find mention of it anywhere. link?