Connecting Win7 to WinXP requires password?

I just bought a Win7 PC. My office network is all WinXP PCs using Server 2003 and static IPs. All PCs are shared with no reservations and Win7 is networked as "domain.network".

To access a drive on one of the XP PCs, Win7 prompts for a User and Password. I can use my Administrator credentials or ANYONE's user/password on the network. It retains that info only until I reboot it.

So how do I get Win7 to trust itself on the network without User & Password? I have scheduled programs that must access folders on networked drives, and I don't want everyone having to type user/password to get to others PC drives?

Thanks