You can also buy a new AMD RADEON HD 4870 which is slightly better than AMD RADEON HD 5770! The AMD RADEON HD 4870 costs $59.99 and is a very good video card! If you want to play the newest games on maximum resolution and settings you should buy AMD RADEON HD 6850 for $139.99 which is way better than both AMD RADEON HD 4870 and 5770!
A Radeon HD 4870 is slightly faster than a 5770. I've picked up several good used ones for about $60 here in the U.S. Just remember that it uses more power and runs hotter than a 5770. I actually have a 4870 that I'm trying to get rid of, but the shipping to Pakistan would make it too expensive.
They will both run fine on a 450W PSU, but the 4870 needs 2 PCI-E power connectors.
Guys, he is not in the US, He is from Pakistan, please note that before giving him another suggestion. It's not as easy to find hardwares at Pakistan compared to the US, as the OP may only find 5770 at $90, maybe it's easy to find another good cards at US, but not at Pakistan. And the PSU will be also not supporting the 4870. It has only one PCI-E connector. If the OP plans to buy a 4870 from US, he maybe getting up paid more than $100 even then the original price was below $75 .
Dude i am in pakistan too i have 5770 and 1440x900 and i love this card runs BF3 on ultra, 30+ FPS, seriously 5770 is 1000% better choise then 4870. having dx11 rocks, its the future as so many games now days support it, and you just have 720p monitor so you can max out dx11 games, and trust me you will love it.
2 GB is really not necessary for that card, 2 GB is for cards like 5970 etc
buy a new 6770 1 gb as its same as 5770 but a modified version.
it will work flawlessly on your 450 watt PSU...