I'm not a networking guy by all means, I'm just a developer who dabbles enough to get into trouble and I'm there. So bear with me... :)

At my office I have a Windows 2003 Domain Controller which also services DNS. On the domain I have a handful of computers and other misc. equipment/toys. For the DNS I only created a Forward Lookup Zone for my domain (mydomain.com). I run a lot of VM's so generally I have everything on the domain, however some of those VM's are not and only in a 'Workgroup'. I also have another laptop which belongs to another domain (otherdomain.com) which is here 100% but I use it for other purposes and has to belong to the otherdomain.com.

With all that said, I have two questions:

1. I have found any computer not on mydomain.com does not register it's IP address even though 'Register this connections address in DNS' is set to in the 'Advanced TCP/IP Settings' for the nic. Where have I messed this up?
2. On the laptop which is registered on otherdomain.com, when I do a nslookup for a computer on mydomain.com (e.g. nslookup devbox1) it appends otherdomain.com as the suffix (e.g. queries devbox1.otherdomain.com). Same thing occurs if I use the fully qualified name. In the 'Advanced TCP/IP Settings' for that nic, I can 'Append these DNS suffixes' of mydomain.com but I fear that will hose my DNS lookups when I VPN to otherdomain.com. So what is the correct approach to resolve this issue? Do I add both mydomain.com and otherdomain.com in that order?