But that other one would work, right?
Yes but you will more than likely be sharing system ram with the card at 256 on board. If $$ is the main setback then it will work. But performance may not be any better than just staying with the onboard. The whole point in upgrading is to go with something better and reduce system resources used. The cards I linked to will have there own dedicated memory and the one you linked has only 256 ram and will be a lot slower and most likely still need som of your system ram to support it. Remember Vista according to the minimum
Operating system: Windows 2000, XP or Vista
Processor: Pentium 4 2.4GHz or AMD equivalent
Memory: 1GB (Windows 2000/XP) or 2GB (Vista)
Graphics card: GeForce 5900 or ATI 9600 Pro / X600 (128MB)
Audio devices: Sound card
Input controller: Mouse with scroll wheel
Optional controllers: Joystick, Joypad or Steering wheel
You are already just barely meeting the specs with what you have.
any increase of graphics and Graphics memory will take some of the burden off the cpu.
Your system doesn't even meet the specs required.
Here are your dxdiag specs for your comp
Processor: Intel(R) Pentium(R) Dual CPU E2140 @
1.60GHz (2 CPUs), ~1.6GHz
Memory:
2038MB RAMPage File: 1435MB used, 2877MB available
Display Memory: 256 MB
Dedicated Memory: 0 MB
Shared Memory: 256 MB