Mapped drives requesting password???

Recently I have added 2 new PC s to a workgroup (User 1 and User 2) they both XP professional SP3.
At first I could not access my shared drives (on User1 and User2) but after setting password on User 1 and User2 I was able to access my drives.
Now the problem I have is that if I change my passwords on User1 and User2 to something different then what it was I will no longer be able to access shared drives on User 1 and User2.
Is there same sort of security policies that I need to now about in order to disable password request when accessing shared drives and be able to change user password on User1 and User2.
Your answers much appreciated