[/b]DisablePagingExecutive=1[/b] is a win even with relatively small (by today's standards) amounts of memory. I think I used it even back when I had less than 512 megabytes of memory? (but still not enough memory to disable paging completely). Paging drivers and kernel components to disk should sound pretty self-explanatory bad to everybody, I think. The reason it's being done at all is that NT was designed when systems had very little memory.
And windows tends to page things out to disk a bit aggressively, or so it would seem to me. DisablePagingExecutive=1
helped my system "recover" back to a usable stage (ie., stop disk thrashing from pagefile read/write) sooner, on the low memory systems, when I had exited something very resource intensive like a game/whatever, it was definitely measurable. Sure thing, turning that setting on meant that games/apps had slightly less RAM available for their use, but I was happy to sacrifice that to avoid the "thrashing recovery" after running intensive stuff.
I still have the setting on, but have been running without paging file ever since I got a gigabyte of memory, so I don't feel it's effects at all. This box has 2 gigabytes of memory, and it has never been a problem running without paging file. As soon as I can get my act together and transplant harddrives + graphics card, I will be running from a quadcore with 8 gigabytes of ram (there goes my savings...) and hopefully I'll never ever need to even consider using pagefile again