Performance issues after hadware upgrade

The situation:

Intel core2 6400 Processor (dual core, 64bit)
64bit Windows XP Pro
High end nVidia graphics card, latest drivers
1GB RAM


The problem:

If SL is allowed to run on both CPUs performance is very poor. This is a known issue, and is worked around by configuring SL to run on one CPU only (task manager -> process -> set affinity)

This boosts the typical frame rate from 4fps to 8fps, with the CPU running SL at a constant 100% usage. This is still a lot below my old system (18month old ATI graphics card, single CPU, Windows XP 32bit)


The Goal:

Make SL playable on this modern system that has no trouble with any other games or applications, including both graphically intense apps and CPU intensive apps.


The Questions:

Why does SL have such severe issues if it runs on 2 CPUs? Other applications and games are all quite happy with this setup, even ones not written specifically for dual CPU environments. Is there any workaround that will all me to use processing power from both CPUS (as per a normal application on a dual core system)

Am I correct in assuming that the performance bottleneck is CPU power? Is there any better way to see what is causing the performance issues?

Why am I getting less performance now than I was previously, when even a single core has more raw power than than the old CPU? Even my company laptop manages SL better than this, and it's hardly a gaming system.

Does SL hate 64bit OSes? (I don't expect it to gain any benefit from a 64bit OS, but other 32bit apps run fine and I need 64bits for some unrelated things)

Why is SL chewing up so much CPU power? What is it doing with all those cycles?

Are there any plans for improving client performance? (This is really a question for the Lindens, but I'm hoping someone remember a recent answer since I'm sure it gets asked a lot)

Hi,
Tried to find Affinity in Processes of Task Manager in Vista, isn't listed.... LOL.. more MS controlling crap no doubt