I've got both a black MacBook and the entry level MacBook Pro. Both are Intel Core 2 Duo. Got the MacBook in November for personal use and then ended up with the Pro for business in February.
Hands down, I prefer the Pro. The fit and finish on the MacBook Pro is of the highest quality. The MacBook is plastic, feels cheap, and is developing cracks after minimal use. I still like it, but I'm a little disappointment with the regular MacBook's overall quality. I have an iBook G3 500 that I got in 2001 and that thing was well built. You could drop it on a table with force and feel confident that it won't be damaged. Unfortunately, with the MacBook, I'm afraid to put it down gently on a soft surface.
In terms of graphics quality, I can't really say because I don't play games but I do know that the Pro has dedicated graphics ram whereas the MacBook shares its ram or something to that effect. This is noticable when you hook up the laptop to an external display. With the MacBook, if you have screen spanning turned on, you'll notice a choppier screensaver on both machines. However, with the Pro, there is virtually no difference.
You'll also notice that the Pro has a crisper screen. The resolution is much better and you'll notice this when comparing the two machines side by side. Go to an Apple Store to see it live.
If you like portability and 15" is just too large for you, go with the MacBook. Even though mine is cracking, it's still a good travel laptop to shove into a bag and get on your way. But if you prefer a more solid machine and if you are willing to spend the extra cash, get the Pro.
Note that I don't use my machines for game. I strictly use it for surfing, email, writing, music, and photo storage. Despite the fact that I'm not a graphics or video pro - nor do I play games - I still prefer the MacBook Pro.
My two cents.