Have a look at this page: click here
It tells you what cards will work.
If you're looking to play games, none of the cards will enable you to play the latest games at full resolution, but you probably know already that you can't afford one of them.
My laptop has an Ati 9700 chip and I can play most games at reduced resolution and some of the fancy stuff turned off.
You can probably get a reasonable card for £80 and a very good one for £130 - is your birthday coming up soon?