CAD user and rare gamer here
The 260 is the best performer of the bunch but the 5770 has "set the price" for the category and to my mind all three are way to high. The 5770 is a good buy at $140. The 4870 is good at $150 and the 260 at $155. But all of them are over $175 last time I looked (excluding no name cards)
As far DX11, none of them can do DX11 ...at least not on your 1920 x 1200 monitor. Yeah I know that the 5770 has a DX11 label slapped on it but if you read the THG review for Dirt2, even w/ the game's modest DX11 implementation, it simply can't play the game at 1920 x 1200 and maintain a minimum frame rate above 25 fps. Before there's a slew of "driver update" posts, the cards shortcoming is its bandwidth.
So you're left with DX9/10 performance and here the 260 / 4870 are about 10% faster than the 5770.
The value of the 5770 in particular is clearly not going to be in its performance. Compared to AMD’s 4870, it loses well more than it wins, and if we throw out Far Cry 2, it’s around 10% slower overall. It also spends most of its time losing to NVIDIA’s GTX 260, which unfortunately the 4870 didn’t have so much trouble with. AMD clearly has put themselves in to a hole with memory bandwidth, and the 5770 doesn’t have enough of it to reach the performance it needs to be at.
If you value solely performance in today’s games, we can’t recommend the 5770. Either the 4870 1GB or the GTX 260 would be the better buy.
Our jobs would be made much easier if AMD had either made the 5770 perform at parity with the 4870, or made the 5770 cheaper. Right now on a good deal we can swing a 4870 for $140, while the 5770 will be sticking to $160. That’s 14% more for a card that performs 10% worse. If we take a linear extrapolation, the 5770 needs to be at around $130 to win on performance alone, or at the very least $140 so that we can talk solely about the 10% performance loss versus the extra functionality of the 5770.
So here’s the bottom line for the 5770: Unless you absolutely need to take advantage of the lower power requirements of the 40nm process (e.g. you pay a ton for power) or you strongly believe that DirectX 11 will have a developer adoption rate faster than anything we’ve seen before for DirectX, the 1GB 4870 or GTX 260 is still the way to go.
But again, with all the cards in this category overpriced, I'd recommend upping the ante to the $200 category in the list below. If you want future proof w/ DX11, I'd say the entry point for 1920 x 1200 is the 5850 but even that's going to be strained with the games of XMas 2011 if not 2010. Here's the results of THG's December roundup. I'd ook at the options in bold.
http://www.tomshardware.com/reviews/geforce-310-5970,24...
Here's the "winners" from THG's latest (December) GFX Roundup
Best Graphics Cards For The Money: December '09
$50 - HD 4650
$65 - HD 4670 / 9600 GSO
$85 - 9600 GT
$95 - 9800 GT / HD 4830
$110 - GTS 250 512 MB
$120 - GTS 250 1 GB
$155 - HD 5770 / GTX 260
$200 - HD 4890
$240 - 2 x GTS 250
$310 - No winner (HD 5850 Honorable Mention)
$330 - 2 x GTX 260 / 2 x HD 5770
$400 - 2 x HD 4890
$410 - No winner (HD 5870 Honorable Mention)
$465 - No winner (GTX 295 Honorable Mention)
$625 - No winner (HD 5970 Honorable Mention)
As for the 2-3 years, I'd be more comfortable with a i7 (920), especially for CAD, and a CPU / GFX upgrade at the 2 year mark....I think that would give you 2-4 years of productive usage.