Problem Connecting to DB from Forms on Win 95

BackGround:

I am trying to Install Personal Oracle 7.1 & Dev/2000  on my System running Win 95. I got the CD along with  my purchase of the book " Oracle Unleashed" ( Sams Publishing ).

I am able to start the DB. I am also able to access the DB thru SQL Plus 3.2 . I am able to run Forms 4.5 demo applications that do not access the Oracle DB.

However when I try to run any application that uses any DB objects I get ORA-3121 / ORA-12203 error. For some reason Dev 2000 Forms is not able to connect to the database.

The only "fishy " thing that we noticed was a warning while  installation of Dev 2000. It said

"Install Cannot find NSDW.DLL in your path . Make sure one and only one NSDW.DLL is available and is in your path. This may cause SQL*Net APPC to fail . "

Interested in the following :

1. What is NSDW.DLL ? Where do we get it ? Is it part of Oracle OR is it part of Win 95 ?
2. Why am I not able to connect to the Oracle DB from Forms ?
3. Has any one used the Dev 2000 with the Oracle DB in Win 95 env ?