Wow, crazy thread.
For clarification, I think "hitching" means "hard drive caching/accessing" I'm not sure what noob coined the term "hitching", but I guess I'll have to get used to it.
Ok, when a system pauses because of hard drive access, you should see the hard drive LED come on (usually the red one on the computer case if you have it connected properly). This is normal for all ATA drives since it takes a lot of CPU power to pull something off a hard drive - SCSI gets around a lot of this by having their own processor. I'm not sure how S-ATA or NCQ fits into this since I haven't really played with one of those drives yet.
Anyway, this has almost nothing to do with your video card. It will happen on any system where the hard drive is being accessed. It can be made worse if you're using highest-quality texture settings in a game. Because if you run out of Video Ram and System ram, the hard drive will be used as a temporary storage space. Since the hard drive is much slower than ram, you will notice pausing when the hard drive needs to be accessed. Again, this has almost nothing to do with your video system (except for texture sizes), and you need to find out what's accessing the hard drive.
Some hard drive caching is normal for some games. Lets say you walk to a new area/checkpoint and the game saves in the background. It has to access the hard drive, so you will get a pause, no matter how much ram you have.
If you want absolutely no hard-drive caching at all, you'll need to check these things:
1. Make sure you have enough Video RAM / System RAM for the game and settings you're using. 2gb of ram is recommended for new/future games. If you don't feel like upgrading, then lower the texture quality settings in the game - this will make them use less memory.
2. Kill all background tasks before playing a game. You should have no virus scanners/spyware scanners/system utilities/etc running in the background while playing. Press ctrl+alt+del in Windows to see a list of processes running - end all of them that you can. You don't need that NVcontrol panel, NVhelper, and most other applications that may be running in there.
3. In Windows XP, disable services that are not needed. Search the net for a windows xp service tweak guide to see which ones you can get rid of. All of these start up with your system and use system memory.
4. Check the AGP acupecture size in your bios (for AGP users only, I'm not sure if there's something similar for pci-e users). Normally it should be 128mb for most games, but higher and lower settings will have different effects on different games.
Now this thing about nvidia chipsets causing problems with nvida cards is most likely not what you're having. I believe this is when you get pauses in the game not related to hard drive caching - like you're running around in a game and it all of a sudden skips a frame when you go past a wall. If you walk back and forth in front of the wall, it keeps skipping the same frame. I've actually noticed this on my ATI card, with my nforce3 chipset, so I'm not sure what the deal is. It's hardly noticable though, so I don't think this is your problem.