What are the optimum computer components for video conferencing?

My mother has a Dell computer with a speed of (I'm guessing) 1 gigahz. It is about 4 to 5 years old. Is this good enough for viewing video conferencing with a broadband IP? She can't travel and I am undergoing chemo treatments. This and other factors has resulted in a 2 years since I have seen her. I suspect it doesn't have much of a video card and probably 250 to 500 meg memory. So where is it best to optimize the video conferencing components: memory, or video card, or cpu speed? I don't have much money to spend on it being upgraded.

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