If your Dad's business uses SQL you can do this one of two ways, depending on how much use the database gets, (From the sound of it that will be option 2 due to how light the use on the database appears)
Option 1. If using hyper-V you can have a second VM which is purely a SQL machine, this will give you the best performance for your money, but will cost you an extra license and additional money on hardware depending on the machine you have been spec'd
Option 2. You run the SQL database within SBS 2011, which will be backed up by the SBS Backup tool. This will add some more strain on the server, but as long as the hardware is spec'd correctly you will be fine (additional ram basically)
SBS 2011 standard is the best cost efficient method for your business, I will agree on that and has features in it that you currently do not use, but you may use in the future (specificaly internal e-mails )
I am happy to hear you have got multiple quotes, you might want to check if the new guy has his SBS Specialist (The older one) or SBS Competency (The new one) as these show he is skilled with SBS to the degree Microsoft would like. I would have to argue that you do not always need someone who knows your dental software inside and out, I support many companies who's line of business software I am not familiar with, as long as there is a support contract with the supplier of the software we can get any issue resolved within reasonable time. We have migrated software as well by contacting the supplier and speaking to them on many occasions.
SBS 2011 performs a block level backup, so can easily be restored, but what you are talking about is a Hardware Independant restore, I can confirm there is software on the market for such restores: [url="http://msmvps.com/blogs/bradley/archive/2007/08/17/storagecraft-hardware-independent-restore.aspx"]Storage craft By Bradley[/url] (Bradley is a Microsoft MVP for SBS) and the shadow protect is hardware independant, but you need to ask yourself how fast would you need to be online if things went down, simply from a cost point of view. If you do need help with Shadow Protect I do have a lot of experience with it, and find it the best backup software I have used.
I do not see a reason to visualise for 1 server, reasons being its a waste of power if you are only going to be using the one server on it, and it will slow down restore times as you would have to restore 2 servers, the host machine (with hyperv or vmware) and then the guests, which will take longer then a normal restore would.
Your best bet for good advice would be one of the following places:
social.microsoft.com/Forums/
forums.bit-tech.net
http://msmvps.com/blogs/bradley/contact.aspx (if you contact her she might be able to recommend people in Germany for you, I know she has a lot of contacts. )
Oh and I have signatures turned off as I cant load pages on my phone with them turned on.