You need at least 2GB of RAM to run it on Vista, as it has been stated before, so it may work. If your graphics card isn't memory hungry.
To put it in black and white...
With minimum RAM and below minimum proccessor speed no guarentees can be made that it will run smoothly.
Saying that people have managed to get it running before in the past. My laptop ran it jerkily on XP wil 1GB RAM and 1.8GHz.
If you do buy it dont be expecting it to be perfect, however, if and when you do decide to buy it, you can help boost your RAM if you need to do so by using a 4GB USB and using readyboost to help speed things up a bit.
If you have another computer ie desktop at home you could always try it on that failing it running on the laptop, as laptops aren't as powerful/advanced as the desktops at present.
Hope that finally puts to rest any fears you have