Long overdue, but the one I liked and thought it was unique was the ECS 945GCT-M, with 2x 16x, one of which is electrically 4x.
About the quote from the wiki, Tom's HW or Xbitlabs did an experiment to see whether a 16x video card is influenced by the 16x, 8x.. 1x. They just taped the surplus connections on the PCI-E side of the card and plugged it in. Some documenting was made before, they didn't just tape it. Their result: 16x is better than 8x, so all those with 2 cards in SLI or Xfire would have benefitted from upgrading their 2x 8x to 2x 16x. Nowadays, most boards are dual 16x, so no biggie there.
But, it proves that even the mightiest cards they used (before DX10) were capable of working at even 1x speed. Maybe someone else read the article.. and remembers it..
Anyways, looks like a good setup you have there. If the gigabyte board has nice OC capabilities, you could buy the cheapest core 2 you can and OC that.. A really fast single core could be better, but not an older P4.. Does anyone remeber the highly OC 805 CPU? It could get 4GHz+ but it is not so competitive today... And this is an old generation dual core. I'm going with the others and crenn on the dual core. Much better.