Intergrated mic as in at the top of laptop screen....well, as a hackaround you might try clipping a piece of lightweight foam across the opening ( imagine the black stuff that you can get for wind noise ). I can see how a regular pop screen design would impede your screen vision. Are you completely against spending money on this issue?
Besides that, it might be possible that the data processing used by your VOIP provider is just really shitty...known to happen...you can check this by recording from your your mic into Wavasaur or w/e to a .wav file, and listening back on ( half decent ) headphones. If it sounds good, the problem is not your setup.
As far as realtime VST processing it's a fair bit of fooling around, I guess you'd have to find a way to route Reaper's or VSThost's http://www.hermannseib.com/english/vsthost.htm
output to your VOIP proggy. You won't be able to even start that before installing ASIOforALL http://www.asio4all.com/