Jay,
I think you have it backwards. In my experience in VFP, Sybase 11 and 12 with large datasets (>100k rows), NOT EXISTS is significantly faster than NOT IN. I can provide a performance benchmark later.
>I'm not sure about that. You have a correlated subquery here which requires that the subquery be performed for each record of the result set in the main query. Tamar noted this a couple weeks ago, and that's SOP for other SQL implementations AFAIK. I think the original NOT IN syntax would give the preferred performance.