When shopping for a laptop, graphics are a thorny question. A little extra performance is always good, as it will probably come in handy someday. But the more advanced the graphics solution, the more likely that it will consume more power, and generate more heat, shortening battery life, and keeping you from actually putting it on your lap.
In the general case, integrated graphics solutions have come a long way, and are more than sufficient for most real uses. Let's face it, email, report writing, and browsing the web are not the most graphically intensive things in the world.
Games? You wouldn't use that laptop just to have a little fun when there's more important things you should be doing, would you? ...Let's get back to that.
There are other tasks that demand a bit more from a system. Any sort of graphics creation/processing will, at the very least demand more RAM from the system. For regular art or graphic design needs, this is system RAM, as this is needed to hold a lot of data not visible on the screen. In general, more is always better, as it is always possible have graphics that need more RAM, but 2 GB is a good target with current prices and technology.
Beyond that, there are 3D applications such as computer animation and CAD/CAM design. For a student in such fields, it is probably well worth making sure your laptop can easily run such programs, which means getting a dedicated graphics despite the cost in power and dollars.
A word about Vista: Vista features a new interface style (Aero), that requires fairly hefty graphics processing (read: dedicated graphics), since it has a fair amount of 3D eye-candy. However, this feature can be turned off (and there are reports that it shortens battery life, so it might be a good idea to turn it off), and it does not come with Vista Home Basic, so a machine with that version won't need it anyway.
Finally, the real use of the laptop needs to be considered. It is very tempting to want to get a high-performing machine that can... play games. And if it is your only, or primary machine, it may need to cater to this. If you already have a desktop, and this is intended to be of use for taking notes in class, or writing papers in the library, try to keep that mission in mind.
And even if the system is going to play games, current integrated solutions can run them. But a high-quality or large laptop, with a large pixel count will still overload this, and a 'performance' laptop should be performance in all aspects, not just processor or screen quality. If just a few casual games to pass the time are desired, any sort of current dedicated graphics will do, if the desire is for current and future games, look for for more recent DirectX-10 (Vista) capable graphics, which means any ATI Radeon part with a 'HD 3000'-series number, or nVidia GeForce '9000'-series.