Why cant i connect my new computer to talktalk broadband modem?

I have bought a emachines computer which is loaded with vista home. i cannot seem to get it onto the internet with my broadband router even though it worked with my old computer. is there anything different about vista that i need to be aware of?
Answer
Make sure you have installed the software for the modemif you have it maybe a compatibility issue with vista you may need to download a a upgraded driver as there are problems with vista