Sapphire HD4770 512 DDR5 VS. Sapphire HD4850 512 DDR3

Depends on the needs, low power consumption, 4770, slightly better preformance, 4850, better performance at higher resolution, 4850 1GB because there is no 1GB 4770.

It does require a PCI-E connector so you will need a reasonably modern power supply but any decent 400 watt and up power supply will have enough for it.

It depends on your needs, when i built my system the 4770 was more than the 4850 for lower performance so i went with the 4850, but if you were going to be putting it in a place with limited cooling or power options or need quietness i would get a 4770.