Nice to see this thread resurrected! As heyhey says, it's not a good idea to put cooked food in a normal compost bin, though rats may also be attracted to a bin as a nesting place.
Tricks for this kind of bin include placing the bin on top of a large square of guinea-pig or birdcage wire and wrap the wire up around the sides of the bin - this will stop rats from invading. Also, turn your compost often as rats don't like disturbance. Plant strong-smelling plants like lavender, cat-mint, garlic etc around the bin, sprinkle cayenne or other pepper around it.
There are other types of composting systems for food waste, do check out
www.stopfoodwaste.ie for free advice from the Irish EPA-sponsored Stop Food Waste programme. I'm working on the programme, so anyone can PM me for further advice as well.