If you're only configuration is via a tnsnames file, you can delete the sqlnet.ora file and it'll look for the tnsnames.ora file by default.
The sqlnet.ora file is handy if you have names (defunct) or an ldap server (Oracle Internet Directory aka OID). Here's why.
NAMES.DIRECTORY_PATH= LDAPSERVER1,BACKUPLDAPSERVER,TNSNAMES (surrounded by less/greater than symbols)
That way if LDAPSERVER is down, BACKUPLDAPSERVER will be used for connection information, and if that's unavailable it'll cascade to your tnsnames.ora file in $ORACLE_HOME/network/admin. Perty nifty, huh. Personally, I like the idea of centrally managed connection information store.
Sounds like you have a simple client side configuration, so, party on.
PS. Davey, US thanks you for Paul Oakenfold, best thing from UK since the Beatles...