I am glad that you understand the inportance of a good PSU when getting a new video card. I would not be using a 3 year old PSU with a new power hungry video card.
I checked the power consumption, the GTS450 doesn't use that much more than 8600GTS. maybe 10~20W in full. Since the minimum requirement for GTS450 is 400W, while my psu got good amp at 12V and actually rated as 500W so I thought it should work.
Just wondering if my system will bottleneck the card. Thx.