OK, newbie Q...

I got my EOTech 551 the other day, great sight, love it... cant stop shooting the thing.  I was looking into lights and i have no idea what i should get into.  I have an M4A2 (Eagle Arms preban lower, cant think of who made the upper...) and its bone stock barring the EOTech.  

Now, i want a decent light, but since the grips are already small, do i have any other options?  I dont want to lose any of the functionality (i.e. i want to keep the iron sights, bayonet lug, grips, etc)... so can anyone reccoment a light/mount for indoor/outdoor illum which wont overly crowd the hand guards (i like to have a place to grip, but dont like verticals) but still be very useful?

I'd prefer not drill the handguards if possible, but if this is the only way, i'm all ears!

If you don't want a vertical foregrip or other accessories on the front of the rifle, you might want to check out the SureFire 500A. It is a nice unit, very compact & reliable. With the standard small head it puts out 125 lumens with the standard lamp or 225 with the optional lamp. The newer models have LED navigation lights on the left side, in either white, blue or red.

I have two 500s, one very early model without nav lights and one new one with the white nav lights. I have had absolutely no problems with either one of them. With the 125 lumen lamp the unit gives all the light you would need inside a house or in the area around your house. The run time on the 125 is about an hour with fresh batteries, and only about 20 minutes with the 225. I have cleared a lot of buildings with mine, & I have never needed any more light than the 125 puts out.

[url]www.surefire.com[/url]

How does it mount?

It replaces your handguard.  the M500a is a molded handguard fashioned after the double heat shield M4 handguard with a light module molded right to the side of the handguard.  check Surefire's web site for more info.

or You can also get a side rail attachment to your existing handguard and mount a light to it. minor drilling on your handguard is required.

You can also get a front sight tower sling swivle from GG&G with a rail on the side which can be used to mount your light.

You cna also buy a under the forearm rail and mount a light to it.

GG&G makes a ring that will hold a flash light and bolt right into the vent hole on your handguard

Surefire makes a barrel mount or front sight tower mount for their light.

It all depends on how much your want to spend, the M500a is a bitchen looking unit which will break most guy's wallet, and down to getting a side rail mount which will require some drilling of your handguard and that is your cheapest option.  

Since you have a CQB optic and it seems you want to keep it light I suggest a 6V Millenium with ARMS mount on a Wilson front sight light mount.  That way you can mount it to the right or left side and go either tail switch or tape switch.  Just ditch the ring for mounting a 6P.  Use the HO bulb and your good to go.

Never be afraid to ask a stupid question so here goes: being new to the weapons, I can see what a laser site would be used for and it's benefits but whats the lite used for (other then actual tactical situations)..?

Laser is for chasing cats around, an IR laser with NVD is something military take full advantages of to fight in the night.

Light is to ID targets, to blind and confuse the targets and to help you get from one point to another in the dark. never keep the light on, lots of strobbing fast on and off and move your position.  low light combat is an art.