4Gb RAM and Vista 32bit pagefile

With 2gb RAM and Vista Ultimate on my PC, I found that (unlike XP) several
hundred mb would be written to my pagefile (2 pagefiles on 2 drives)
especially after exiting a demanding program or game. I measured this with
Doug Knox's XP Page File monitor program.

I recently added another 2gb RAM to my PC a 4gb total. Well the PF activity
has been reduced considerably but still I would see up to 40-70mb on each PF
after about an hour of PC usage or a playing a demanding game.

This in contrast to XP where the peak PF acivity would be no more than 3 or
4 mb after heavy usage or a tough game. Why is that? I would have thought
that 4gb RAM would eliminate any PF activity.