I've switched from 4 Gb ram (with pagesys file) to 8 Gb ram (without pagesys file) on Vista 64 with an already build Raid0 array (150 MB/s read outpout) and it changed everything !!!
I also took a USB2 key drive for vista readyboot feature (works quite well actualy).

I'm running 4 copies of WoW and when I'm in Dalaran, the follow doesn't break anymore.. I can also flight (280%) over the city (for 8 sec) without breaking the /follow either.
Before my Ram upgrade It took 6 minutes to go from the Alliance Inn to the krasus area for my 4 toon, which were constantly breaking follow. I was considering changing my return stone to another Inn like K3 or the sewers.

Anyway ... be sure to upgrade to 8 gb of ram before changing anything else in your setup
And I think that a 64 bit OS is far easyer to install than a 32 Bitwith tweaks just to get the whole 4 GB active