Thank you to all !!!!
took me about 10 minutes to work my head around how to get mobi2mobi working, but now I've got the hang of it and my problem is solved!!! Its a lot quicker than Calibre even though I have to do extra typing...
I still think its a shame that PRC input into Calibre and then changing metadata results in Calibre having to convert the PRC back to html, change the metadata and then create a new book as a MOBI file... its silly! going to let Calibre know about this problem.... PRC export would save a lot of hassle.
Thanks again everyone !!!