which is da best video/web conferencing soln? What shuld be the key things 2 look for in free or paid solns?

I am a small business user. I need to use conferencing solns.. the ones in which I can talk/ share files/ show presentation etc.. with any body , anywhere.

I am looking out for a good conferencing soln, Freeware/shareware or paid services…But i need to know which are the critical things- that i need to check up before singing up with any body.

Who are the key players offering such services?

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