Move Office selfcert sig to another PC

I created a digital signature using the selfcert.exe program in MS Office, then exported the signature to a network share and imported it onto other computers on the network to allow them to use the macros I write and digitally sign. I'm getting ready to replace my PC, and don't see a way to copy or move the signature; the exported signature works to run macros, but not to sign them. I know I'm being cheap and will likely end up buying a 'real' key that can be saved and moved, but, is there a way to use the selfcert signature on another computer?