Choose sponsors based on the games you choose or choose games based on the sponsors you choose.

E-club Malaysia - CS, L4D, L4D2 or any valve game
New Era - Activision
SMM - Blizzard
TSB - EA Games

As a college community, you could also approach companies like Intel or AMD, depending on who provides the pc's to your college/university.
A solid year-long proposal should be sufficient, although you might want to look at web-development and database development to attract more people over a long term basis.
Work together with online media such as spotgamers.com and multiplay to extend coverage on your event.

Most sponsors prefer to provide in kind rather than cash, so sometimes, you'll need other methods to gain cash.

Hope this helps.