Light Bulb ?'s

Hello again

I have been keeping a few live plants.  They were/are
doing to good.  First let me say, the tank is 20g planted
w/ angel fish {2} pH 6.0 ammon0.0 nitrite.0.0
So the water seems to be ok. I went down to the local
pet store (petland} He of course explained to me
that I need more/better lighting.  I was using a FS. 
So he sells me a Penn Plax Ultra Tri-Lux. Now the 
question. :  Is this what I should be using?  Right now
I have swords, crypts, hairgrass. Nothing fancy.
I paid a few bucks for this bulb. I need to know if It will
keep my plants alive.  This bulb has been in only 2 days.
I'm thinking that I may have to put the FS back in.
As always any/all help will be greatly appreciated. {sp?}