The 5770 will do fine.. However, CPU bottlenecks occur at low resolutions such as yours.. Which processor are you using currently..?? A full system spec will do good..
CPU bottlenecks for graphics-intense tasks occur at high FPS (in general, of course). If all he's looking to do is play his games at a reasonable framerates with some AA, then even a low-end Athlon X2 will be fine.
Hope you have a faster single core processor or dual core.
I have the same card and i play call of duty all at 1920x1080 at max settings with high frame rates. Also Fallout, burnout paradise give me max settings with max AA.
But i have a core 2 duo..
As others said it depends on your CPU. What are your system spec?
Well if you really want to see what it can do i made a personal review on www.frozentec.com , go to the review section and read.
1280x1024 - at this resolution you should be able to max out the games, i do not know about gta4, but the ones i tested run with flying colors, also to ad, avatar will run at that resolution with all max out, crysis warhead also, and i doubt that gta4 won't work with max settings. Also i overclocked my card easy, and you can control the fan speed from the soft(catalist control center) witch you need to download from www.sapphiretech.com
Ok... This mean there are a lot thing that CRT cannot do but LCD can do it right..?
Maybe i will grab LCD to... cause i want to have a good view when play game... Hehe.
It's not that an LCD can do more things. In fact, an LCD is mostly stuck at one resolution, unless you are ok with a less crisp image, while a CRT can easily change to what ever resolution you want, up to it's max, and it is always crisp. LCD's also don't look as good at angles, but this should not matter, unless you are watching someone else play on your comp.
However, an LCD does not flicker if you have a low refresh rate, due to being solid state, and as a result, they are easier on the eyes. LCD's also take a lot less room, and generally look better.
The quality of the image depends on what LCD you buy. If you can get your hands on a 2-5ms GTG response time(better 2 GTG milliseconds) and also be full HD(1920x1080) or 1920x1200 witch has the color white really white not gray or yellow(try to see the difference) and if you move from one side to the other the colors no not change or they change so little that you can barley see then buy it.
Check the color black also, make shore that it is a dark black not gray.
Probably a 23' would be nice.
Also before buying it find a review on it and see what others think or reveal about it.
The issue is more that your CRT is likely 17 inches which is very, very small compared to even reasonably priced LCD screens. I would recommend getting a nice 1680x1050 22" monitor. The difference in size and resolution will be remarkable compared to your current screen and the HD5770 will still perform very well.