Well, it depends. You don't really need a video card if you just use your computer for surfing the internet and whatnot.
If you want to game or do professional work, then a video card would be in order.
What are the specifications of the computer and what is your budget?
It is a Pentium(R) 4 CPU, 3.4GHz
2GB of RAM
Radeon 9600 XT AGP (0x4152)
Memory- 128 MB
Bios Info: BK-ATI VER008.015.051.001
I would like to improve video editing on this computer. I looked into buying a new one but for a time being I can't effort the machine good enough for avchd editting. Right now the Vaio is really slow, maybe with some improvement I can give it a little boost.