Replying to Aluminum MacBook vs. White Polycabonate MacBook

Recently it was my 16th birthday so my dad is going to buy me a MacBook to replace my dying Acer. Anyways, I've done a bit of research but haven't gone to the store yet. I know I'll learn alot by talking to an Apple store person but I also would like to have an unbiased opinion first (cause the new aluminum one is more expensive)...and since NS seems to use MacBooks alot i thought i'd ask my questions here. First of all, here are the specs on each.

White Polycarbonate MacBook

• Intel Core 2 Duo
• 2GB DDR2 Memory
• 160GB hard drive1
• NVIDIA GeForce 9400M graphics
• Standard keyboard
• White polycarbonate shell
• $1,149 CAD

Aluminum MacBook

• Intel Core 2 Duo
• 2GB DDR3 Memory
• 160GB hard drive1
• NVIDIA GeForce 9400M graphics
• Standard keyboard
• Aluminum unibody
• $1,399 CAD

I'm pretty sure they both come with the iPod touch rebate if someone could confirm that, thanks. So my questions are what is the difference between DDR2 and DDR3 memory? Will it make a difference? Also, how much difference will the .13 GHz make in processing power? Is there any software upgrades in the aluminum macbook? Also how is the new trackpad on the aluminum one? Which will be more durable? Is there any like really standout reasons I should buy either?

Thanks NS.