I recently bought my first Mac and had this same dilemma between refurb old pro or new Macbook...
My reasons for buying the new Aluminum Macbook 2.0Ghz from the point of view of a Windows/Linux user who's favorite laptop line has always been T series Thinkpads:
Refurb MacBook Pro:
-Known Defective GPU, Apple has extended warranty to 2 years but no recall and no indication that if they replace your logic board you will have a non time bomb 8600GT (although you could gamble that if it fails in two years they will give you a current Macbook Pro).
-Replacing Hard Drive in Macbook Pro is difficult and is not considered user replaceable.
New Macbook:
-The new macbook (just like every other Mac) is overpriced for its specs (CPU/RAM/HDD/Mediocre screen). This is not obvious if you consider MSRP prices on PC's but unlike Apple hardware which goes on sale for $50 off on boxing day, PC hardware is always on sale and you don't need to pay anything near MSRP.
However I think the new Macbook has some unique qualities worth the price:
-The new unibody is really awesome, the laptop is extremely solid with no flex. It really feels like a premium machine.
-The huge trackpad. As i mentioned earlier I love Thinkpads and the little red nub in the keyboard and have always hated trackpads. The new trackpad is huge which makes it much nicer than older styles. Also since the trackpad can sense where you are clicking the lower right hand corner can be used to right click. This is a huge feature if you happen to think that one mouse button is simply not enough. (Correct me if I'm wrong but the button on the old Mac Laptops was just a single button, so no right click without pressing command?)
-Noise and Heat-the new Macbook is amazing. This feature alone is a huge deal if you care about how much noise your laptop makes. From what I've read the old Macbook pro's had heat issues.
-9400M chipset is really nice for power consumption and 3D performance. This isn't a unique feature since it will be in PC laptops in the next few weeks.
-These are the unique things that I don't think will be duplicated in the PC world for a while and make the price worthwhile.
Another line of reasoning for buying aluminum Macbook is that it is a slim and portable at 13". In the real world (not the Mac World), laptops that are small and portable generally cost more than the the bigger laptops. If Mac's where priced like Sony's you would pay more for the portable Macbook over the Macbook Pro. An example is the horrendous price of the 17" Macbook Pro's. They start near $3000, meanwhile I've picked up a well equipped 17" HP laptop for $750 from a retail store.
I just wish that HP or anyone other than Apple could have made these laptops (I don't consider OS X to be a huge plus), then I could have nice aluminum laptop for under a thousand dollars when they inevitably go on clearance after a few months.