Since this is a topic that seems to come up over and over and over in KAL's I participate in, I thought I'd just blog and link instead of repeating myself. ;o)
Knitting isn't handed. It simply isn't.
You use both hands to knit, just as you do to drive. There are different actions for each hand as you drive (the turn signals are usually on the left, the gear shift on the right, etc.), but nobody talks about left-handed drivers or right-handed drivers, or left- and right-handed cars.
Mystique swirls maddeningly around lefties learning to knit, and thickens the further back you go in time. One lovely lefty lady at my old LYS, Rachel, was taught to knit standing in front of a mirror. Her instructor (a Righty) insisted it would be easier for her to learn that way. But it's really not necessary. If anything, Lefties have an edge in learning to knit, because as has been pointed out more than once: in Continental knitting the left had does more than the right. Elizabeth Zimmerman even called Continental Left-handed Knitting. Check out how I (a definite Lefty) knit:
There are only a few stitches in that clip, but watch my hands (not fingers) carefully, and see which hand does what.
More examples are here and here.
Learning to knit backward can be handy, as it makes button bands and other small pieces easier (turning every four stitches is crazy-making). But beyond eliminating the need to turn your work in such situations, it's borrowing trouble (as is mentioned at the bottom of the page here). Knitting backward under all circumstances means that you must read charts backward, reverse written directions, or have a mirror image of what is being knitted. But more than that, it creates a mental barrier that can grow all out of proportion. Whether in your own mind, or the mind of knitters you meet, habitually knitting backward places obstacles in your way that needn't be there.
Long rant short, do yourself a favor: learn to knit Continental in the conventional direction. It's fast, efficient, and despite requiring an initial investment in time and effort, will save you hours and hours and hours of frustration and work in the long run.
And learning an already-entrenched skill in reverse is excellent for your brain. ;o)