We would recommend against using WON. It is no longer possible to use WON to go online, as you probably know.
Installing ESF to a 'normal' HL1 installation, and thereby using WON to play, also results in many more bugs, compared to when you'd use Steam. This is another reason why we recommend using Steam.
It is possible to play offline with Steam. ESF 1.2.3 comes equipped with bots for offline play, and Steam itself also has an offline mode. Therefore, I believe it would be best for you to use Steam anyway.
Yea Im not gonna front I did download it off the web only cause my locl gamestore didn't have non in stock the guy said that he would be expecting some more games on thursday . And I had read an post saying you can play using WON I was just gonna play offline against bots until thursday so that way i can have experiecne and still enjoy ESF til I can play online