right now i'm using a very old laptop so the graphics card won't let me do anything in unity and i'm buying a new laptop tomorrow and i just wanted to know if a 400 hundred doller compaq or a HP laptop would have a graphics card high enough
Any card that supports Pixel Shader 2.0 should be fine.
Unity's Minspecs:
System Requirements for Unity Authoring
Windows XP SP2 or later; Mac OS X "Tiger" 10.4 or later.
Graphics card with 64 MB of VRAM and pixel shaders or 4 texture units. Any card made in this millennium should work.
The rest only depends on the complexity of your projects!
I wanted to add that a Laptop is really not the best platform to develop a game on. A solid desktop is going to get you a lot more bang for your buck, particularly in the video card arena. There are exceptions, but if you only have $400, a Desktop is a much better option.
As for Pixel Shader 2.0, this was introduced with the GeForce3 series of cards (Radeon 9000 series), I don't think you could even find a computer without a card as GeForce 3 came out about 9 years ago, but with laptops, it's a gambit as they tend to be hacked-on cards to reduce heat and power consumption. Definitely check the video card specs before you buy.
You'll probably need to go online to find the specs as clerks generally have no idea about the specifics of a video card and will just tell you "Yes, that will work" to get the sale.