Hey there ritelec,
It seems like you are wanting to know if you will be able to reinstall Mac OS X Leopard in the future if you ever need to. That won't be a problem and you should be able to install it again per the following article:
When the installation is done, you'll also be able to update it with:
Thank you for using Apple Support Communities.
Have been on Snow Leopard since a little while after it came out - on the upgrade on my Mac Pro - had one program that required an upgrade - and that was 3rd party database program that was cheap so guess thats how they made the dollars.
You may want to check compatibility of your software with snow leopard. and get the hard copy of it.
Have not updated software since because like you - had needs that came before wants.
Sad to discover Apple doesn't realize there are people who dropped expensive high speed cable/internet for slower less expensive connections and antenna TV.