How can i know if a video card is compatible or not with my computer/motherboard?

Hello, well, the problem is, i don't know that if i buy a video card will it be compatible or not with my computer... I've seen in the internet mentioning about PCI Express, PCI, and AGP, but i don't know which type is my motherboard... My motherboard is Intel... Intel G31/G33 exactly... Please help me on this, my PC sucks (Intel Graphics Accelerator rubbish) and My laptop can't be used too long... So I need to improve my PC... If it turns out that my PC can't be improved, well I'll Just stick to my Laptop... Again, Please help