Yes you can program the side buttons on the mouse which are called mouse forward and mouse back. However, since you are a lefty you may want to consider a mouse from the likes of razer who make a left/right mouse. However, dual handed mice usually don't have the side buttons for some odd reasons. Which leads me to recommend one that has 2 buttons that are 1 on each side.
As far as being a righty for the keyboard, the Merc Zboard Fang, or Thermaltake Flare keyboard should do you nicely for both lefty and righty set ups since its made for both.
I use a 7600 creative labs 2400dpi mouse and a merc zboard. I do have a mx518, but the 1600dpi I feel is not high enough to keep it snappy.
