Stacking spells?

[Max Caysey]

Does Regenerate Light Wounds and Vigor stack?

Thanks

[Andezzar]

Ask your DM. Regenerate Light Wounds is 3.0 and the book it is in has not been updated to 3.5. As such the DM is encouraged to make adjustments so that the content is compatible with 3.5. What those are only your DM can tell you.

[Cruiser1]

Does Regenerate Light Wounds and Vigor stack?
No, because they both grant fast healing 1. Similar to this, casting Resist Energy twice (at low CL) gives you resist fire 10 twice, instead of resist fire 20. Having both spells up does at least give redundancy, meaning they both need to be dispelled to remove your fast healing or fire resistance.

[Karnith]

Regenerate Light Wounds is 3.0 and the book it is in has not been updated to 3.5.
Regenerate Light Wounds itself, however, was revised for 3.5 as Lesser Vigor (http://www.wizards.com/default.asp?x=dnd/dnd/20050110x).