Can you network Windows XP and Windows Vista together??

I have just recently bought a laptop and it has Vista on it. Where as my Desktop computer has Windows XP and my laptop is connected to the router and is able to get on the internet. But i cannot see my desktop computer on my laptop nor can I see my laptop on my desktop in the network tab and I can not share files between these two computers… But I can share files from another XP that I have in my house. So i know it isn’t a Network problem. Is it just some problem that Windows Vista has? I know Vista has a lot of those…