To put things in perspective for you.

I was running a dual core E6600 with 4g (3.2) on vista 32 bit with an 8600GTS.

Best i could do was 30fps on the main and 15 on the alts. I was constantly losing alts while mounted and pip swap was laughable.

I first upgraded to a Q6600 and was getting 35 fps on the main and 20 on the alts. But i would lose alts while mounted and could never have crusader aura on. This was with all graphics set low except view distance at 50% on the main. Pip swap time was about 1-2 seconds or more depending on whats happening around me.

I then upgraded to Vista 64-bit and am adding more ram as it comes. at 5gb atm. Now things run at 35 fps on the main and 20 fps on the alts. Pip swap time is now under a second ( even while pvping) and i have yet to lose an alt while mounted with crusader aura up running at 120% run speed. Havent had time to test out running through shatt yet. But things are a vast improvement.

When i finish upgrading to 8gb of ram i doubt ill have any issues at all anywhere.