I'm looking for some advice here, rather than the big how to do it I'm looking for what do to

I have this home server, quad core and 4 GB of ram (I really can't afford more right now). With a Windows Serve 2008 R2 With ActiveDirectory and a Hyper-V-Virtual machine with SharePoint, TFS and a couple of more thigs.

I have a least 10 remote users, all of them joined a Hamachi VPN (working great by the way). But I want to migrate that to a Small Business Server 2011 Standard.

I tried to make a VM to join the domain and then promote that VM, back up it and then format the physical server, boot up the VM, Promote the Phisical and then erase the VM, but I can't do that because of SBS requiring a least 4 GB of ram to install (so I can't give all the 4 GB of physical ram to a VM).

I was thinking in using a laptop (All the clients are laptop) as a temporal server, join the domain, promote it, then format the server and install SBS on the server and do all again.

I really need some advice. Thanks in advance.

BTW, I know that the software I'm using is kindda expensive, and I can't afford more hardware. I have access to MS downloads by a University partnership so I have all this software for free.