The simple questions about plain old pots and pans are sometimes the ones that drive you crazy. The shopper who ventures into the stores looking for a nice little pot to cook the rice in or a frying pan for the hamburgers is faced with a far more complex set of variables than he who goes in search of a fluted pa te' en croute mold.

The simple truth is that sometimes you have to invest a lot of money to get the pot you want. But often you don't. The trick is in deciding which is which.

In general, characteristics that separate the cheap pot from the expensive pot have to do with the efficiency and subtlety with which the pot gets the heat from the stove to the food, and not necessarily with how long the pot is going to last.

Subtle heat conduction is important in operations like saute'eing and fine saucemaking, but not of the least moment when it comes to many of the everyday operations that every cook performs. Even the cheapest pot, unless it happens to get run over by a bus, is not likely to actually fall apart. It may warp or develop hot spots where the metal wears, allowing quicker transfer of heat, but its basic structure will remain intact.

On the other hand, there are cases in which the best pot for the job is likely also to be the most expensive.

If the average household divides pots into two types, saucepans and frying pans, it makes much more sense to concentrate resources on the frying pans because most of what goes on in the average saucepan doesn't require subtlety or instantaneous control over the heat. It usually doesn't matter much if there are hot spots or warping in such a pan.

In a 3-quart saucepan, for instance, which tends to be the basic workhorse of any kitchen, you boil rice or potatoes, you heat up soup, you cook vegetables, you boil milk, you make hot chocolate. None of these operations requires much delicacy.

The cheapest choice would be a thin-gauge aluminum pan, the next cheapest one of the less-expensive brands of stainless steel. Then would come the variations: anodyzed aluminum (such brands as Calphalon or All-Clad), tin-lined copper and finally the fancy stainless at the most expensive end of the scale, such as that made by Cuisinarts.

In a standard 1 1/2- or 3-quart saucepan, the choice that makes the most sense for most cooks is the cheapest stainless steel you can get your hands on. This will be slightly more expensive than thin-gauge aluminum, but not much. And, stainless has some properties that make it preferable in a saucepan. For one thing, it doesn't react with acid foods like tomato sauce. This reaction, especially if the food and the metal are in long contact with each other, can cause the sauce to taste like the inside of a tin can. Stainless is also easy to clean.

Next you will probably need something really big for cooking spaghetti or boiling corn. In this case, stick with plain, old, cheap aluminum. There are some big pots on the market, for very little cash outlay, that are boiling pots with two steamer inserts and can serve multiple purposes.

If you make fine sauces like hollandaise or temperamental custards like cre me anglaise, consider investing in a small, tin-lined copper or heavy-gauge anodyzed aluminum pan like Calphalon or All-Clad. Thinner, cheaper pans will not be responsive enough.

Among frying pans, the workhorse of the kitchen, at least in households of two-to-four people, is the 10-inch pan. It's the one that's big enough for four hamburgers. In frying pans, the cheaper, thin-gauge aluminum or stainless will not serve you as well. Bad effects will be caused by the poor heat-conducting abilities of the metal, and by the tendency of these pans to warp and develop hot spots. The fact that frying pans are often subjected to higher heat than saucepans just adds to these problems.

A warped bottom or hot spot doesn't matter much if you're heating up soup or cooking potatoes, but it does matter if you're saute'eing onions or frying hamburgers. In a pan with a warped bottom or hot spots, the onions on one side will burn before the others are cooked, or one hamburger will be done before the others.

The best choice here, if you only get to choose one, is probably heavy-gauge aluminum, preferably anodyzed to neutralize the acid-food problem. Calphalon fits the bill very nicely, as do the All-Clad aluminum pans that are lined with a thin layer of stainless steel for easy cleaning. These pans are expensive, but their properties fit perfectly with the work they will be asked to perform.

If you're not worried about the acid-foods question, take a look at the heavy-gauge plain aluminum pans made by Commercial Aluminum or Leyse, or by one of the French manufacturers. They are cheaper than the anodyzed versions and have exactly the same heat-conduction properties.

Some people would vote for black cast iron, which is cheaper than aluminum. However, it's slow to respond to changes in temperature, so, while it's perfect for things like bacon and fried potatoes that require steady heat, it's probably not the best choice for all-around frying pan.

The worst choices are plain stainless steel or any combination in which stainless predominates. If you are feeling expansive or do a lot of serious cooking for which instant regulation of heat is important, begin thinking about copper, either tin- or nickel-lined. It will be more expensive than heavy-gauge aluminum, but there is no material like it for control.

Finally, most households need a simple pot for making stew or chili. This is another place where a little investment -- this time in an oval or round, 5-quart, enameled cast-iron Dutch oven or cocotte will pay off. You can saute' the meat and vegetables in this pot, then add the liquids and let it simmer away. Because of the properties of the cast iron, it will simmer on the barest of flames. You can also do pot roasts in it and, if you've bought the oval shape, a whole chicken.

So you've got a cheap saucepan or two, a cheap spaghetti pot, a more expensive frying pan, and a more expensive cast-iron Dutch oven. For a modest investment you've got pots and pans enough to do nearly anything the average kitchen requires.