How far the light should be from the plant?

Hi, I'm starting my first grow and I was wondering, on the circumstances there are, I would like to know how far my grow light should be from the plant. I'm going to start off with a 5" pot and 3" of it is filled with soil. The grow light is a 150 watt. I dont have much detail about it because I bought off of amazon. Here is the link to it:
http://www.amazon.com/Hydrofarm-LKIT150-Dayspot-150-Watt/dp/B000053F9K/ref=sr_1_9?ie=UTF8&s=home-garden&qid=1265852981&sr=8-9

How far should the light be away from the plant?

about 4 -6 inches if your startin seed

4-6 at mimimum, though you MAY want to go higher depending on heat. Weird thing, i just did alittle search on your kit but found very little as to specrum and such, if i had checked more i may have, so anyway go 4-6, but if you see any signs of heat stress life the light up alittle at a time