While some may simply answer "Nvidia" or "ATI" without adding anything else when asked about it choosing the right video card for a certain hardware/software setup user needs and budget can be quite tricky especially when your video card- and computer-related knowledge is at the same level as my quantum physics proficiency. Well... let's leave any other mumbo-jumbo aside and let's talk about the main things one must keep in mind in order to make the right choice when choosing a video card without any expert around shall we?
Potential Hardware/Software Problems
1. Especially when choosing a powerful video card for gaming but also true for most mid-range possible choices your PSU may not be able to provide enough power to your new piece of hardware - be sure to check that your computer can deliver enough juice to it or you may end up with a brand new card that doesn't work as it should... or even worse! To check your computer's power requirements take a look at this page - your computer may be already underpowered so better take a look at this page no matter if you're planning to get a new video card or not.
2. A budget video card can easily handle most modern games if you're still using a monitor that has a native resolution of only 1280X1024 as I do. On the other hand if you want to push all game settings to the max and you're going to do that on a 32-inch display... not even a card located in the upper area of the mid-range category won't be able to get the job done every time. Best place to see how a certain card handles various games in various resolutions? Click!
3. Sometimes your case may not allow you to mount a large card - be sure to check the size of the card and the available space inside your computer's case before making the purchase not after! ;)
4. Don't get more than your system can handle if you're not planning to upgrade all of it soon - having a $300 video card on a computer that's worth $300 without it doesn't make any sense trust me! The idea is to get a video card that's not too much for your processor-mainboard-memory to handle. Again there's no need to have an expert to tell you that - just take a look at the page I mentioned a bit earlier there's plenty of information for you there!
5. Never underestimate the need to cool down of your new hardware piece! Depending on your case and its airflow as well as other things (the average temperature inside your computer room to start with) a video card that usually runs hot may overheat. No need to tell you what can happen due to overheating right?
6. If your computer runs Linux be sure to check the dedicated user forums to see what kind of driver support/issues you may encounter with your choice(s).
User's Needs
1. If your old video card is broken and you just need a replacement for working with documents and checking your email there's no need to spend big bucks for this - just get the cheapest card you find - even a second hand one will be fine.
2. For viewing HD movies on your computer you may want to try a video card that can take care of the movie decoding part - most recent video cards from ATI and Nvidia can do that but you also need a media player able to mess with those features of your hardware (SPlayer for example).
3. If you encode videos a lot then it seems Nvidia cards hold the upper hand here. As expected the more powerful (and expensive of course) the video card the better its video encoding capabilities.
4. Games - nothing special here after all - the bigger the better right? On the other hand after carefully considering the software/hardware issues that you may encounter you may also want to check some benchmarks of your favorite games - while some games rely heavily on the GPU others also need a powerful processor so you may want to spend less on a new video card and divert some of your finances to a processor upgrade as well.
User's Budget
When it comes to hardware upgrades (but not only) the more money you got the less headaches - you can just go for the highest-end products and that's all! For really low budgets there's no new video card to get the job done but you can grab really good older ones for your money - for example you can't find any decent gaming card for under $60-$70 but you can surely grab a used 8800 GT/GTX for about the same amount.
Sure there's no surprise that as your budget goes up - and depending on your needs of course - there are interesting choices from both AMD/ATI and Nvidia. I am not going to talk about any other specific models - such things change but the basic idea will always be the same - do some research before anything else there are plenty of tests available online to help you decide what your money can really get!
The Myth Busting Part
1. "Nvidia cards are great ATI has problems with its drivers." or just "Nvidia rulz ATI sucks!" are two phrases that come from those people who walk this earth without a purpose probably because natural selection doesn't always work too fast. FALSE! Both companies always had great products on the market each offering a "best bang for the buck" card for a certain price range. ATI had some serious driver issues more than a decade ago. Now when driver-related problems occur it's usually because game producers bother more to make their games run great on Nvidia cards or... because you didn't bring your drivers up to date yet. ;)
2. "CrossFireX/SLI setups double your PC's gaming performance." FALSE! While having two or more video cards inside your computer can surely increase performance the resulting framerates/rendering capabilities are not double/triple. Depending on the game they can get pretty close to that but they're usually somewhere in between. One thing's sure on the other hand - your computer's power requirements will get up faster than its performance! :P
3. "I need a powerful video card to run Windows 7 properly." FALSE! Unless you also want to play some games that need a powerful video card even a contemporary integrated GPU can handle Windows 7 pretty well.
4. "More video memory means a faster video card." Nothing more false!!! It's the same as saying that a car with a 3.6l engine is faster than one with a 2.0l one but without giving any other details about the technical details. The GPU really matters other than that... it's better to have 512 MB of GDDR5 memory instead of 1024 MB of GDDR3 or even worse GDDR2. Same thing goes for bandwidth sometimes - a 256 bit bus card is not necessarily faster than one sporting a 128 bit bus.
The End
Well... I don't think there's any need for a special conclusion because I already said it a few times in a way or another - be sure to think and research before purchasing a new video card for your computer. At last there's no problem if you go ahead and ask us about your video card upgrade ideas/needs - we're always glad to help!
That's all folks! ;)