Just wanted to report my post-patch findings here. My specs are generally a 2.8G with 1G RAM and an Nvidia 256K video (FX 5600) with the 81.95 driver.
I uninstalled the game and reinstalled it, then without trying the game I loaded the patch. I had some sort of problem with either the original install or the patch, I can't remember which, where it had some sort of something it couldn't find in dealing with the stuff that's created in the My Games directory, but I gave it an ignore after retrying it and it seemed to work. I suspect that the unistall didn't uninstall these directories and so it bumped into them again, but I was too much in a hurry and didn't bother reading anything. I figured I would bother to read if I had to do the process all over again. On the patch, I got the familiar 1673, or whatever code, but just plowed through that as others have, to no additional difficulty.
About the game itself. I have played the original disk on both huge and large, with almost exactly the same results, in that it would do the memory leak bit after I had got into approximately the midway point of the tech tree.
I'm about at that point in the game now, for what is about 4 hours playing, and there's not the slightest hint of the bad stuff it was doing before. Even the wonder movies are working superbly. The only thing that leaves me wondering if it will CTD again is that there was one instance where the map details disappeared for about 4 seconds. There was also another time, where the French, who I had made several contacts with earlier in the game, had a decent sized delay that had me worried. After those two glitches, you couldn't tell in the least that it affected the game, as the speed was back up to what it had normally been doing. It also used to be that saving the game took like 2.0-3.0 seconds. Now it takes like .3 second.
I'm running the game at like 1280 X 960, and other than that everything else is pretty much stock, including the autosave.
I have noticed, however, that the barb and animal ratio have been "seriously" tweaked in this game, compared to before. I probably explored at the rate I had for the unpatched version of the game which just on a wild guess means that by the time my recon gets through those units have been through like 30 battles, which of course gets a lot of promotions. In this game I had "maybe" 5 fights total and not a single promotion. I might had seen like 5 barb units the whole time, which includes some of my recon being in the booneys for extended periods. I used to could count on running into at least 5-6 animal units in the snow areas alone, but I don't think I found a single one there. Very different. Looks like I'll have to turn raging barbs on.
?. Except for this the patch has been perfect
.
reinstalled directx9c just to be sure (the day before I had just upgraded to the latest nvidia drivers, which ran fine for me with the unpatched civ4 version), emptied my temp folder (as it also contained a copy of setupapi.dll), rebooted a couple of time and started civ4 with the shift key pressed in (I believe I read somewhere that this would empty the cache).
There are stil some minor problems with some of the animations. And its gets slow at the later stages post 1900AD. Movies does not work had to disabled it. 
