Regarding netbook vs notebook: <what sully said>
I'd just toss out there the HP Touchsmart tx2z. It's a convertible tablet (screen swivels around to be purely a laptop or purely a slate tablet) with a multi-touch touch screen (ready for Win7 touchy goodness).
Specs: AMD Turion dual core, up to 8gb memory, up to 320GB 7200rpm hd, ATI Radeon HD 3200 graphics w/ 64mb mem, 12.1" screen, built-in dvd burner, webcam, N-wifi, bluetooth, etc.
I've been toying with the idea of picking up one for myself to play with win7 and *nix. It won't play crysis, but it would be a fun laptop with a very small price. Iit is right smack dab in the middle, pricewise, of a gaming laptop and netbook prices ($1500 vs $250).
Like i said, just thought i'd toss an idea out there.
Regarding going from 2.0 to 2.5Ghz. When i overclocked my 2.4Ghz Q6600 to 3.0Ghz, i *did* notice the difference in the peppy-ness of the system though i don't have any actual deltas in fps to give you. To get pretty close... i checked out this site for benchmarks (
http://www.techreport.com/articles.x/14573/5) they say the difference between a 2.6Ghz and a 3.0Ghz Core 2 Duo are:
Bioshock (+300Mhz gets you +2fps)
Supreme Commander (+300Mhz gets you +2fps)
Team Fortress 2 (+300Mhz gets you +15fps)
LAME Audio Encoding (+300Mhz gets you 3 seconds faster)
You can review the benchmarks yourself to get an idea. Mostly up to you if you think it's worh the delta in price.