How can I specify different domains, network shares and printers?

I have SBS 2000 running on a server at work and the same running on my server at home. I recently purchased a new laptop and want to be able to connect to either system by selecting the domain from the logon dialog depending on which system I am connected to (my computer name, my username and password are identical on both systems). The two systems are completely separate and physically some miles apart so I don't think I can use AD trusted domains.

I installed SBS on my laptop using the setup disk while connected to my home network, everything works correctly. I then took my laptop to the office and installed using the SBS setup disk from my work server. Again everything works correctly but my home domain is no longer available for selection, I was hoping it would be added to the logon domain dropdown list instead it was overwritten.

I can connect to my home domain again by plugging my laptop in at home and then using the Network ID wizard to 'join' my home domain. This is obviously a long drawn out process just to switch domains each time I move between home and work systems. I have also noted that the ISA Firewall client stays set to the last value despite the fact I have two separate profiles stored (Tony.domainhome and Tony.domainwork).

I have tried altering registry values under the WinLogon key such as DefaultDomainName and AltDefDomainName etc. to try to make both domains available in the logon dropdown but to no avail. I have also added the key NoDomainUI which removes the dropdown list and allows me to logon using Tony@domainhome or Tony@domainwork this is semi successful but only gives me cached account information for the last domain that I changed to with the Network ID wizard.

So, I have a two-part question: 1. How can I make both domains available from the logon dropdown list so that I can switch quickly and easily?