Well, the basic difference between AMD and Intel chips, is heat management.
AMD T-bred chips and latest Barton chips don;t even need any additional coolers.
Intel instead, should be provided with a Tornado at least.
Also AMD's model number naming, instead of Intel's BUS frequency naming, creates some confusion to new buyers. So people compare AMD +2500 price, with Intel 2.5, which are far different.
As for graphics, ATI and Nvidia have different customer targets in market. So to speak, they don't go into each other's way. ATI targets professionals with requirements in OpenGL, ultra stability, and with no need to overclock:P
Nvidia is more D3D than GL, so gamers all prefer GFX, which is better than ATI when used that way.
I am Intel fan personally, but AMD and ATI user since last winter. And have no complaints.
Cheers