You're free to have your opinion about waiting, but as Neil321 pointed out, "Nehalem will smoke Montivena." Nahalem, once it's complete, will be nearly 50% faster than the Penryn processors that Montevina will utilize.
Penryn (using the Montevina chipset) = 2 cores
Nahalem (using the Montevina chipset) = 4 cores
You're doubling the number of CPU cores with Nahalem - that will be a substantial change.
Why do you think all notebook versions of Nehalem will be 4 cores?
Please cite your sources for such performance, I do not think that is correct at all:
Wonder how you're going to shoehorn a 4 core into the tiny enclosure of a MB, MPB 17in might get quad but don't expect to see it on a lower price point MB until 25nm process tech around 2011 or so. MB will likely get Nehalem after the MBP, which may not get Nehalem until well into 2009. Even Penryn/Montevina has been delayed a few months.
As far as the desktop versions of Nehalem, performance on some apps, *not* all apps is a little faster, probably not anything a freshman in high school is going to notice, better to have that Blu-Ray drive option

.
Also note in the pre-production test here TDP is the *same* as Penryn

, don't expect identical performance from the lower TDP notebook CPU's.
http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3326&p=9
With a larger socket and more pins, the CPU itself is obviously bigger. Here's a shot of our Nehalem compared to a Core 2 Duo E8500:
Final Words
First keep in mind that these performance numbers are early, and they were run on a partly crippled, very early platform. With that preface, the fact that Nehalem is still able to post these 20 - 50% performance gains says only one thing about Intel's tick-tock cadence: they did it.
We've been told to expect a 20 - 30% overall advantage over Penryn and it looks like Intel is on track to delivering just that in Q4
Hardly consider that 'smokes' anything. But if you need higher performance for games, then better integrated GPU's that Intel will have with Nehalem, might be worth the wait. Only limited instances will the performance matter that much, and all the while the classmates who already have MB using Tiger & M$, are gaining valuable
experience on how to use those OS's, something a newer model computer can not give you. Worry more about learning to know as much as you can about software apps and the OS, rather than hardware geek tech.
You can do most things a desktop Mac does, on a notebook, just they will take longer. Stuff like intensive computational things, in video or photography, example:
PTGui Pro, 4 cores 3.5Ghz and fast Raid-0, I/O between storage and CPU is limiting factor, need more less expensive, really fast SSD's if you want to complete some 200+ megapixel multiple stacking/blending of images with something like PTGui Pro, otherwise you can count your wait in hours, not minutes!