That's because you asked the wrong question.
so I'll ask you the right question and if you give me the right answer, I'll give you the right answer ;P
Question: which new late 2007 iMac? the 20" or 24" model?
Good camera, I have one too.
There is no info on an updated MacBook yet, only a product release history on which we can expect an update in the october /november time frame.
Probably Santa Rosa MacBooks with a modest speedbump of the C2D to 2.0 and 2.2GHz.
Get a wirelessrouter or use the one you got from your profider.
Because, If your brother want to use internet your iMac has to be active and your iMac's performance will decrease if he starts some haevy surfing.
primatelabs Geekbenched the new 2.8GHz 24" iMac.
iMac (24" Mid 2007) 2.8GHz Intel Core 2 Extreme = 3791
iMac (24" Mid 2007) 2.4GHz Intel Core 2 Duo = 3243
If you read through the test you'll understand the $250 premium of the 2.8Ghz only pays off if you intend to do a lot of processor intensive tasks.