It's true that you need more light on a smaller tank to get the same impact...but I think 74 watts is still overkill. I don't have any problem with algae in my 10g which has 18 watts of light. It is non-co2 but one of my best algae free tanks, and the plants are doing wonderfully with no signs of being starved of light. I think it's worth a try, anyway.

edit: I found a site with a spreadsheet that calculates lumens per square inch and converts it to a wpg rating, thus give a more accurate reading for wpg. When I plug in your numbers, I get 6.24 wpg. That's assuming you have a standard sized 10 gallon tank.

To get it down in the range of 3 or 4 wpg you'll have to go to two NO 20 watts, this will give you 3.3 wpg according to the calculation, I'm also assuming you have T8's.