Mervin,
Frankly, I don't think what you did in your undergrad is going to affect the entry process too much. From my personal experience, the only think I feel counted towards my admission was my undergrad score which was lesser than your score ! Also, as you have more than a year's work experience, that would be a more valid source of evaluation.
About the prerequiste requirement, its more of a formality issue. I'm sure you must've done quite a few common courses with the CS people. Quite a few of my friends have successfully changed their discipline in a similar way. In fact you can account for your work experience to have created an interest in the field of networking or something of that sort !
All the best anyways !
