If you have decided already that you dont want to continue and buy the OEM version, the easiest way to keey your data is to start moving it off your WHS now onto another drive (either on a computer, or on a drive you add but not as part of the storage pool),
Failing that, you can connect the drives to another computer and browse the various directories structures to get your data back.
Option 1 is certainly the easiest and cleanest.
Andrew