Intel NICs: "Pro" series VS Gigabit CT

I was wondering what the differences, other than PCI-Express, were between the Intel PRO gigabit (PCI) series of Nics and the Intel Gigabit CT series (Gigabit CT is not "pro", but appears the same but is PCI-E).

The PCI-E Gigabit CT is only $8 more, so seems like a no brainer for gigabit networking. But, it is not designated as PRO and the pro model seems to be $160 some dollars.... whereas the PRO pci model is a few bucks cheaper than the Gigabit CT pci-express.

What do you get with "pro"? Is the PCI-Express hands down better, or is it a trade-off to get PCI-Express for only $8 more than the PCI Pro adapter??

Intel Gigabit CT
http://www.intel.com/products/desk [...] erview.htm

Intel Pro GT
http://www.intel.com/products/desk [...] erview.htm