DFS replication between Windows Sever 2003 R2 & SBS   

Hello,

We have a Windows Sever 2003 R2 Standard Edition SP2(hostname is Mars) 
running on Intel Core2 Quad CPU Q6600 @2.4GHz and a Windows Sever 2003 for 
Small Business Server SP2(hostname is Doublehelix) running on Dual Core AMD 
Opteron Processor 270 @ 2.01GHz. They are on the same sub-network but in 
different locations and domains(lakescom.net & blcomfor.local). Each of them 
is a domain computer of the other one. Doublehelix has most of our important 
data, applications and MSSQL services only.

A fault tolerance/disaster recovery solution is necessary for us. If 
Doublehelix goes down, users can still access data and run programs on Mars. 

First, we created DFS roots and linked them to share folders on both 
servers, and then tried DFS replication group for data collection on Mars but 
failed. The error said “Doublehelix.lakescom.net: the service control manager 
cannot be opened. Access is denied”. We are not sure if the reason is, that 
not all new functionality (snap in's) are showing after doublehelix upgraded 
to SBS R2, specifically the DFS management console.
Could you please tell me what would cause this problem? 

In our case, is the DFS replication possible and enough for us?
If so, how can we implement it?
Does one domain have to be removed?
Do we need to upgrade one or both servers? If so, which edition (2003 
Enterprise/2008)?
Is Severs-Cluster or High-Availability system applicable and necessary?
Any other solution available?

Thanks,

date: Wed, 9 Jul 2008 11:37:01 -0700   author:   VanBC