[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management]
DisablePagingExecutive prefents system executables from being paged to pagefile.
LargeSystemCache does a lot for gaming and SSD's, as it uses more then 4MB memory, so it caches more.
It does not decrease gaming, in fact it should speed up gaming as your cache is bigger for file operations.
It does not use all memory, but a percentage of it.
Very usefull when you have more then 1 GB memory.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters]
Turning the prefetchers off has no use, as the prefetch helps loading of frequently used data.
It does not adjust all the time.
The registry is written far more often.
Disable 8.3 creation means it also writes filenames in MSDOS FAT format, not so usefull anymore.
NTFSMemoryUsage, tricky one, as it's does side reading...not that usefull.
Will help as it works every 10 minutes when the system is idle, then it defrags boot.
I'm sorry but only the first and last keys are usefull.
However, I miss the more important keys, like logging and counters, you leave them on.
Those are called performance, fileaccess, etc counters, they update the logs, filesystem, etc everytime you click something, turn those off will do a lot more.
Also kill system logging, as those keep writing too.
Don't know the exact keys for Vista, you have to Google for them.
Windows does a lot behind your back