For most of the world, the only reason to even consider a GeForce GTX 550 Ti is rabid Nvidia fanboydom.  A Radeon HD 7750 will get you equivalent performance for cheaper, and while using barely over half as much power.  The 7750 will also be reliably able to use the full 1 GB of video memory, while if a GTX 550 Ti goes over 768 MB, it loses a ton of memory bandwidth due to the mismatched channels.

The next step up from the respective vendors is a GeForce GTX 460 or Radeon HD 7770.  The analysis comparing them goes about the same as when comparing the GTX 550 Ti to the Radeon HD 7750, with only the exception that the GTX 460 actually made sense to buy at times before the 7770 price dropped several months ago.  (For previous generation parts in the respective performance tiers, a Radeon HD 5770/6770 was nearly always cheaper than a GTX 550 Ti, but a Radeon HD 6850 didn't always undercut a GTX 460.)

The Radeon HD 7770 is probably the best bang for the buck in the price range you're looking at.  But your information says you're in South Africa, so you have a narrow selection, which can skew prices.

Originally posted by Storman1977

If you're going to upgrade, then at least truly upgrade.  I would do no less than a GTX 560 (for the same reasons Loke posted) and try my damnedest to get to a GTX 660.

Hell, I'm saving up to get an EVGA GTX 690 Signature, which is complete overkill for most anything on the market...

A GeForce GTX 560 (or Radeon HD 6870) is the next step up after a Radeon HD 7770.  But it's likely out of the budget of the original poster.  Those are both older cards, too, which means much worse energy efficiency.

The GeForce GTX 660 isn't sold to the general public.  Nvidia doesn't have many of them to sell, as is typical for fourth bins of a GPU chip, so it's OEM-only.  Your link goes to a GeForce GTX 660 Ti, which is a different card entirely.  The GTX 660 Ti is a lot more expensive than a Radeon HD 7870 for only a little more performance.  Or at the other end, it's essentially the same price as a Radeon HD 7950 that performs substantially better.  A GeForce GTX 660 Ti can hang with AMD's lineup in a price/performance comparison so long as a game isn't very memory intensive, but will choke of a game wants a ton of memory bandwidth or capacity, of which the GTX 660 Ti has neither.

Getting a single GTX 690 is completely stupid.  If that's the performance level you want, get two GeForce GTX 670s in SLI.  That's nearly equivalent in performance, but a lot cheaper, and avoids the usual problems of dual-GPU cards.  Or better yet, wait for GK110 to launch, though it will probably be spring or summer 2013 by the time they show up in GeForce cards in large volumes.

You will be better off with a stripped down 460 and they are less then a 550. $90 vs $120.

What's your cpu?

Originally posted by Storman1977

Originally posted by jdnewell

Have you considered a 7770?

Good card and a good value unless you are just a must have nvidia guy =)

The AMD cards are really nice, but I believe that GW2 is built on Nvidia architecture and therefore an Nvidia card will produce the best performance.

You might as well believe that the sky is green with purple polka dots.  It uses DirectX, which means that it will work with any card that implements DirectX properly.  It's highly implausible that ArenaNet didn't check performance on several different AMD and Nvidia cards, as well as Intel graphics, before launching the game.  Indeed, ArenaNet's own performance charts showed the game having a slight preference for AMD cards.

Originally posted by thelastradio

Cool I will definitely keep an ATI on the cards. I'm in the market for something in the 550Ti range and power consumption is also an issue, most of the better cards require a better power supply.

Thanks for all the advice, if anybody comes past here and plays with a 550Ti, let me know your experience :)

What power supply do you have, anyway?

A Radeon HD 7750 has a TDP of 75 W, while a Radeon HD 7770 has a TDP of 100 W and a GeForce GTX 550 Ti has a TDP of 126 W.

Actually, what else do you have in your computer?  List your full system specs.  I get the impression that you bought some cheap junk OEM machine and are hoping to upgrade it, which isn't always practical.

Originally posted by nilden
If you get a 7770 just be aware it could do the nasty "Display driver has stopped reponding and has recoved" bullshit.

You know what else could do that?  Every other card ever made, pretty much.  Well, only the ones recent enough to have drivers for a version of Windows that will give that particular error message, I suppose.

Originally posted by thexrated
I just updated my GTX 550 Ti OC version with a GTX 660 Ti OC version. There are some great bundled offerings. Mine came with a free Borderlands 2 for 285€. Sold my old card for 175€.

Convincing someone to pay far more for a used card than it would cost to buy exactly the same thing brand new can make a lot of upgrades look like a good deal.

https://www.guildwars2.com/en/news/bill-freist-talks-optimization-and-performance/

Straight from the devs, the 7970 looks the one to beat. I have the Saphire version of the 7970 OC model and GW runs pretty smooth most the time it still needs some performance tweaks in some areas though.