networking vista and xp

how do you go about getting file sharing between vista and xp on a home network?

Assuming you want to share files on a Vista box to an XP box...
First of all, being on the same workgroup is a big help. In Vista, you have to enable file/folder sharing for networks you are connected to. These options are found in the appropriately named "Network and Sharing Center". After that, it is a simple matter of sharing the folders you would like to share and accessing them from the XP box.

For more detailed info check out this TechNet article: http://technet.microsoft.com/en-us/library/bb727037.aspx

I've had to go in sometimes and under the sharing options, ad the user "Everybody" to the list and give them permission to read/write to the folder before it would let another computer access it (at least on my setup it does this sometimes).