Core 2 Duo is 1 die. 2 cores, no bridge required as both cores are directly hooked up to the L2 Cache. I guess you could say the cache itself is a bridge, but then again AMD are planning a shared L3 cache instead(as well?) of linking its K8L cores via Hypertransport, so it cant be such a bad idea.
Core 2 Quadro isnt a monolithic quad core, as yes, it has a pair of Core 2 Duo dies sitting side by side, interlinked by the frontside bus. Not quite as efficient but Intel did a very good job with the task of avoiding FSB conjestion on Core 2 Duo, So the quads are still very good performing processors.
For most people, a Core 2 Duo offers more than enough processing power, by the time Quad core is anything more than an extremists toy, the perhaps Yorkfield will be out.
Regardless its the overall processor design that counts. As long as the cores can be fully fed with instructions and data, then how they are wired up doesnt really matter. If AMD's K8L quads outperform Intels Quads, then intel will improve them. Never much point in playing the waiting game, there is always something new and improved just around the corner. By the best you can afford that does the job you want.