How Much Faster?

I don't think it's even close to be honest. If your speaking of the 2.0 GHz 2011 15" vs. a 2008 unibody MacBook. Geekbench score for the 2008 is under 3000, for the 2011 it's around 8800. But this all makes no difference if you don't run software that takes advantage of the extra 2 cores of the 2011. If all you do is run Mail, Firefox, iTunes, and Office you would be better served with an SSD. It would definitely speed up your system performance more than adding an additional 2 cores that you would never use. On the other hand, the 2011 will probably offer better battery life, a dedicated graphics card, and Thunderbolt. If you do any actual work with your machine then the 2011 will be much faster.

 

I have both. It's night and day. The 2011 MBP is noticeably faster than the 8-core Mac Pro 1,1 that it replaced. Seriously.

 

Depends on what you are doing. Keep in mind those scores are using the machines to the max abilities. If all you do is internet, email and some word processing, then I suspect you would see zero difference in speed, save for maybe a slight boot up and app opening speed. If you do gaming, more processor intensive things, like video encoding and editing, well then there is no comparison, a faster, mulitcore proc like the new gen will eat even the previous i5/i7 procs.

 

Wirelessly posted (Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5)

Well for starters, the new 15" has 4 cores and the old core 2 duo was dual core. So, that is four 2.0 ghz cores vs two 2.0 ghz cores. Furthermore, architectural changes over the years has made that 2.0 ghz more powerful for similar tasks.