Kevin,
My company is currently developing our Visual Foxpro application into a client/server system using Oracle/SQL Server on the backend and I had to deal with this issue.
The approach I took was to change all my code which references logical fields from "IF
= .T." to "IF = TRUE" where TRUE is a constant defined as 1 and FALSE is a constant defined as 0. Then make sure all your logical data types in Oracle are numeric 1 and can only contain the values of 0 and 1. This way, you'll be able to maintain a lot of your GUI which uses checkboxes for logical data types (by default they'll use 0 for FALSE and 1 for TRUE) and the only thing you'll have to change in your code is .T./.F. to TRUE/FALSE.
Don't forget to define your TRUE/FALSE constants!
Hope this is helpful and good luck!
-JT
Jeff Trockman, MCP