XP Logs On To Server - Doesn

I have a fairly new bog standard Dell business PC with a nice “Vista ready” sticker on it. Partition C runs XP, is trouble free and logs me onto our server without problem. Partition D runs Vista Ultimate and is driving me crazy. I cannot log onto the server (Win 2000), I can see all network machines (and use the internet) and Vista tells me everything is fine. I don’t need other machines; I do need the server’s hard drives. The Vista partition only has Firefox and Office loaded; firewall etc. all turned off. Ipconfig/all returns identical data (where applicable) on both partitions. I have also followed all the advice I could glean the the net. I can get all the way to logging on to the domain (changing from the default workgroup) when I get the dreaded: “An attempt to resolve the DNS name of a DC being joined has failed............”Is the problem with the server? Our IT administrator has left and not yet been replaced so be kind. If anyone needs to see ipconfig or anything else then please ask.