Quickly beat your eggs together in a little jug or cup and set aside.
Stepone: Melt the butter with the water over a low flame in the saucepan. As soon as it comes to the boil turn it off, you don't want your water evaporating away.
Steptwo: Tip all your flour in, in one go (I have it in a cup or jug), with one hand, while simultaniously stirring the water-butter mixture with a wooden spoon with the other. DOnot stop stirring vigorously.
Stepthree: Keep beating and stirring the mixture vigorously until you have a smooth ball of paste that comes away from the sides of the saucepan leaving it clean. This will not take long, a few minutes max.
Stepfour: Now add the beaten eggs, slowly, a little at a time, beating thoroughly after each addition. Don't worry if suddenly you have a slimy mess with bits of the dough seperate from the egg, it doesn't matter, just add all the egg, mixing mixing mixing, and eventually all the egg will be encorporated with the paste and you should be left with a sticky silky paste.
Then you bake them in the oven for ten minutes and then (here'stheimportantpart) you turn the oven up to 220C gas mark7 and bake for a further 7-20 minutes (depending on size) until the buns are crisp and golden.
You should have a tray of lovely fuffed up golden balls (<childish snort>). Now, you are going to take a skewer/small sharp knife/knitting needle and make a hole in the side of each bun to let the steam out. This is important if you want a nice hollow to fill with cream.
Right, once they are cool you can just cut them open enough to fit the cream in using a teaspoon, or you can use a piping bag to squeeze the cream in. If they are eclairs definately just split them down the side.
For profiteroles I would use a tablespoon size dollop on the trays.