Upgrading video card of your computer is a difficult task if you have little knowledge about computer hardware. Video card upgrade in your computer is likely to effect other upgrades in your desktop computer and is also dependent on your computer hardware. If you have a laptop, then laptop video card upgrade is rarely possible. In most cases, upgrading video card of laptop is not possible because video cards for laptops are not meant to be upgraded later. Laptops have tight spaces so upgrading laptop hardware can become an issue and your laptop can also get damaged due to excessive heating.
There are some laptop vendors which provide the facility of upgrading video card and some other parts of your laptop like dell, alienware. But this is limited to only few models of a particular video card brand like nvidia or ati or something else and you just can’t put any video card in your laptop.
Upgrading video card in desktop is much easier. Its possible in most cases with upgradation to other desktop hardware parts if required. But if you strongly want some higher end video card in your desktop, then you may have to upgrade all the major parts of your desktop which may be a not so good thing to do. If the costs of upgrading become high, then its much better to buy yourself a new high power desktop or laptop computer.