Fresh install
Win98, 8i pers.edition (SID=ORCL) and 6i Dev
c:\oracle\orapo c:\oracle\oradev

edited C:\Oracle\Oradev\Net80\Admin\tnsnames.ora
adding

PO8 =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = BEQ)
(PROGRAM = oracle80)
(ARGV0 = oracle80ORCL)
(ARGS = '(DESCRIPTION=(LOCAL=YES)
(ADDRESS=(PROTOCOL=beq)))'))
(CONNECT_DATA = (SID = ORCL))
)

but I get ORA-12174: TNS can't resolve service name
when I try system/manager with connect string "po8"
on sqlplus, same problem with Form Builder