PCI Express

#1 Right now, they're about the same as AGP, honestly. Unless you're interested in the Dual card/SLI stuff.

That'll change in the future, though. You might consider going PCI Express now if you plan to upgrade video cards without purchasing a whole new computer later.

#2 I don't agree with Mark on that one. If you go to the site you can see the difference between the two on there mid range cards
nvidia.com/page/geforce_6600.html

Its mostly a speed issue, but from what Iv'e seen its an all around better deal. Considering that with the new nforce4 chip you can get 3gigs per sec on transfer time. Along with general pci improvements across the board.

I'm still waiting out for SLI myself. Theres a board out now but its 220 bucks. And considering its a 939 chipset, its still too pricey

EDIT: Another thing to note, There has been no real difference between
AGP X8 and AGP X4 while there has been a difference with PCIE X16 due the general architecture changes of the systems themself.

#3 All I can say is, be sure to check independent benchmarks as well as nVidia's specs. :)

#4 I agree. Benchmarks are true. If a manufacturer says that a card is super fast
it is not true, just a selling point to make for the cards.

Also: The motherboards bus must increase if we are to see any real difference.
I never understood why motherboards were the slowest thing in a system. At least now there are some with over a gigahertz.

#5 Like i said above, the mobo's speed is at 3 gigs of data transfer per second. There are a few general improvements overall. Not to mention the overal speed increase with Serial ATA drives in general