Does anyone own this card? I'm thinking about purchasing this card and from what I've read it's comparable to the Gforce 4 4600. I was just wondering if anyone has had any problems with it and if it's a good buy for the money.
"Good buy for the money" depends on the money you're going to spend. Check out http://www.tomshardware.com/graphic/20030714/index.html for a comparison of various video cards, including the 5600.
It's crap. Check the OCAddiction (http://www.ocaddiction.com) reviews on it. In any DX9 based game, this card gets its *** handed to it by the comparibly priced ATi 9600Pro. It does just fine in DX8 though.
256MB isn't useful in any current game, nor any to be released soon. Unless you can run high AA and AF, which this card won't be powerful enough to do and still get acceptable frame rates in DoomIII or HL2.
"It's crap" is more than a little naively harsh. I've wandered through a large number of hardware review sites, and the most objective and professional site is Anandtech. Every other site I've seen has that same mentality when it comes to modern video cards: "nVidia's evil! ATI rules! just look at the HL2 benchmarks!" On that argument, there's a page on shader compilers in the middle of one large review that's interresting (http://www.anandtech.com/video/showdoc.html?i=1896&p=36).
The short is, luck didn't swing nVidia's way this time. However, do not doubt their driver optimizations, they've worked magic before. Benchmarks show better than 50% improvement with 52.x drivers over 44.x while retaining image quality (earlier 5x.x driver has major issue there). Given a little more time, nVidia will be back. By the time HL2 gets released, I'll bet it does perfectly well for itself.
All that considered, I really couldn't advise the purchase of an NV card right now (unless you're talking low-end get-the-job-done-cheap <$80 or something). The brand spanking new 9600XT from ATI looks awfully nice, especially for $200.
But remember, if you can play all your games fine now and are buying for the future, wait for the future and see which cards do better with HL2 and D3 or whatever the next big game is.