I think he was asking if it's possible to do a "system restore" on the WHS box itself.
I had a snoop around about this 'cos it's a damn good question - sadly all I got was that it's a frequently requested feature for a future WHS build.
So it seems that a simple system restore isn't on at the moment, but if the .NET issue is serious for you - I'd suggest re-installing WHS from scratch using the "upgrade" option.
I did it recently taking mine from a late beta to the full version and I found the process to be very easy, and I do believe that WHS is very robust so you should be OK going that way.
Of course, if your have terabytes of data and lotsa plugins to lose - it's always gonna be a scary decision
