mine LTC and dont convert to fiat...convert to BTC.
The exchange rate between LTC and BTC is such that it doesn't really matter which one you mine for...
This is what I've found at the moment. I've got 3 7970s running right now, and I find that if I switch to Litecoin I've made about the same as I would have in BTC in the same time period if I sell it.
I have a BFL pre-order from March this year, so if/when that arrives, I'll probably switch my GPUs to Litecoin to keep things a bit more diverse.