Page File and System Cache use growing

[junk2drive]

i havs noticed some slowdown since installing sp2 when working with graphics or opening folders. i started checking the task manager and noticed that the system cache starts at 170k and as time goes on grows to around 330k while the pf usage starts at 120k and grows to 210k.
i have 512 sdram.
i have mcafee vso, zonealarm, did a virus scan, did the microsoft check for mydoom etc viruses, disk cleanup, defrag.
the only other thing i notice is explorer.exe will grow from 5k to 15-25k and once i saw it at 60k.
i thought i might be a memory leak from one of my programs, but it seems to be doing this with only i.e. and task manager open.
right now after a reboot it shows
total 523k
available 285k
system 310
pf 208

[EzyStvy]

Sounds normal to me.