The 4670 is better by a way (see here: http://www.tomshardware.com/reviews/graphics-card-geforce-radeon,2646-7.html). The higher on the table, the better the card. My 4670 doesn't even need its' own power connector, takes all its' power from the PCI-E slot. I bought the Sapphire HD 4670 1GB DDR3 for a second PC so I don't have any experience gaming on it, never tried. There is also the Sapphire HD 4670 Ultimate Edition 512MB GDDR3 which is totally silent (passive cooled) but you get less memory. In terms of power consumption, it is very good, see here: http://www.anandtech.com/show/2616/9. At idle it consumes less power than the 9500GT and only slightly more at full load. However, it outperforms the 9500GT by a long way. If you are looking for a low profile card (based upon your other thread), they don't do a low profile 4670. However, there is the Sapphire HD 5570 1GB DDR3 HDMI DVI VGA Out PCI-E Low Profile Graphics Card which is around the same price and performs better than the 9500GT as well as using either less or the same power - see here: http://www.anandtech.com/show/2935/13. You could also look at an Nvidia GT220. Whilst not as powerful as a 4670 or a 5570, it is still better than your 9500GT, is cheaper than the 4670 & 5570 and uses slightly less power than the 5570 under load - and they do low profile cards.
The 4670 is an awesome little card, I had it running on a 300W PSU and it just about managed Crysis on High.
