Quote Originally Posted by NecroDOME
You could use major version is the change is major (i.e. new content is required) and use minor version if you only fixed bugs.
1.0 = first release
1.1 = bug fix #1
1.2 = bug fix #2 and #3
2.0 = Some bugs fixed and an extra feature

For internal use you can make a tag in your svn that says "Day of Destruction 1.1". Or you could say simply 1.0.280. But its up to you and more a matter of taste I guess.
Thanks all, I think I might just go with version 1.0 for my initial release, and then follow what NecroDOME suggested

Thanks again to all who have replied

BTW, I suppose I'd have to remember to alter/increment my 'version numbers' manually...I'm expecting to

cheers,
Paul